Develop Reference

asp.net - text boxes lose values entered on tab switch

I have ajax telerik tabs in my code and when I switch the tabs my controls loses whatever I have typed.
I tried "enableViewState" to true. It didn't work either.
What I want is the controls to retain values entered on tab switch
<telerik:RadScriptManager ID="RadScriptManager1" runat="server"></telerik:RadScriptManager>
<telerik:RadTabStrip ID="RadTabStrip1" runat="server" MultiPageID="RadMultiPage1" Width="100%" Align="Justify" >
<Tabs>
<telerik:RadTab PageViewID="RadPageView1" NavigateUrl="CreateNewUser.aspx?TabIndex=0" Text="Adviser Details" HoveredCssClass="hoveredTab" Font-Bold="true" />
<telerik:RadTab PageViewID="RadPageView2" NavigateUrl="CreateNewUser.aspx?TabIndex=1" Text="Fee Split" HoveredCssClass="hoveredTab" Font-Bold="true" />
<telerik:RadTab PageViewID="RadPageView3" NavigateUrl="CreateNewUser.aspx?TabIndex=2" Text="Signature" HoveredCssClass="hoveredTab" Font-Bold="true" />
<telerik:RadTab PageViewID="RadPageView4" NavigateUrl="CreateNewUser.aspx?TabIndex=3" Text="Reference Details" HoveredCssClass="hoveredTab" Font-Bold="true" />
</Tabs>
</telerik:RadTabStrip>
<telerik:RadMultiPage ID="RadMultiPage1" runat="server" Width="100%" RenderSelectedPageOnly="false">
<telerik:RadPageView ID="RadPageView1" runat="server" Height="100%" CssClass="RadPageViewBorder">
<div style="padding: 10px 10px 10px 10px; background-color: white;">
<uc1:AdvisorDetails ID="UCAdvisorDetails" runat="server" />
</div>
</telerik:RadPageView>
<telerik:RadPageView ID="RadPageView2" runat="server" Width="100%" Height="100%" CssClass="RadPageViewBorder">
<div style="padding: 0px 0px 0px 0px; background-color: white;">
<uc1:AdvisorFeeSplit runat="server" ID="UCAdvisorFeeSplit" />
</div>
</telerik:RadPageView>
<telerik:RadPageView ID="RadPageView3" runat="server" Width="100%" Height="100%" CssClass="RadPageViewBorder">
<div style="padding: 0px 0px 0px 0px; background-color: white;">
<uc1:AdvisorSignature ID="UCAdvisorSignature" runat="server" />
</div>
</telerik:RadPageView>
<telerik:RadPageView ID="RadPageView4" runat="server" Width="100%" Height="100%" CssClass="RadPageViewBorder">
<div style="padding: 0px 0px 0px 0px; background-color: white;">
<uc1:AdvisorReferenceDetails runat="server" ID="UCAdvisorReferenceDetails" />
</div>
</telerik:RadPageView>
</telerik:RadMultiPage>
<div class="col100" style="padding-top: 35px; padding-left: 30px; padding-right: 30px;">
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:Button ID="btnAddUser" ValidationGroup="vgUser" runat="server" Width="120px" Text="Save" CssClass="btn-common" OnClick="btnAddUser_Click" />
<asp:Button ID="btnDeleteUser" ValidationGroup="vgUser" runat="server" Width="120px" Text="Delete" CssClass="btn-common" OnClick="btnDeleteUser_Click"/>
</ContentTemplate>
<Triggers>
<asp:PostBackTrigger ControlID="btnAddUser"/>
<asp:PostBackTrigger ControlID="btnDeleteUser"/>
</Triggers>
</asp:UpdatePanel>
</div>
<div class="col100">
<span class="failureNotification">
<asp:Literal ID="litError" runat="server"></asp:Literal>
</span>
<span class="successNotification">
<asp:Literal ID="litSuccess" runat="server"></asp:Literal>
</span>
</div>
Can someone point out the issue pls ?

Your tabs have NavigateUrl property set, which means they render as links, which means they redirect, they do not use ajax.
That's why the values are not persisted.

Click on any link or button redirects to another page asp.net

I have an asp.net web app project which includes total three pages i.e. login page, front page and a page for grid view. When i run the application, it works normally, But when I click any link or any button, it directs to first page. I created even new page also for gird View but still the issue persists. I don't know the issue is in grid view or database. Please assist me in this regards as I have worked a lot on this project.
Here is the code for First page to which it is being redirected again and again
<asp:Content ID="FormContentHolder" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
<div class="container">
<div class="row">
<div id="logobar">
<h1>
<img src="http://localhost:50090/uploads/icons/logo.png" style="height: 99px" /> Document Expiry Alert System</h1>
</div>
</div>
<div class="row">
<div>
<hr />
</div>
<div id="container-fluid">
<div class="col-md-3">
<div id="icons">
<div>
<a href="DatabaseGView.aspx">
<img class="img-responsive" src="uploads/icons/update.png" /></a>
Update
</div>
</div>
</div>
<div class="col-md-9">
<div class="form-group">
<div class="text-left">
<h1>Students Database</h1>
</div>
<table class="">
<tr>
<td class="" style="width: 30%">Registration No.</td>
<td class="" style="text-align: inherit; font-family: 'Arial Black'; overflow: auto; width: 190px;">
<asp:TextBox ID="ID" runat="server" Width="190px" CssClass="form-control box-margin-8"></asp:TextBox>
</td>
</tr>
<tr>
<td class="" style="width: 30%">First Name</td>
<td class="" style="text-align: inherit; font-family: 'Arial Black'; overflow: auto; width: 190px;">
<asp:TextBox ID="FN" runat="server" Width="190px" CssClass="form-control box-margin-8"></asp:TextBox>
</td>
</tr>
<tr>
<td class="">Last Name</td>
<td class="" style="text-align: inherit; font-family: 'Arial Black'; overflow: auto; width: 190px;">
<asp:TextBox ID="LN" runat="server" Width="190px" CssClass="form-control box-margin-8"></asp:TextBox>
</td>
</tr>
<tr>
<td class="">Nationality</td>
<td class="" style="text-align: inherit; font-family: 'Arial Black'; overflow: auto; width: 190px;">
<asp:DropDownList ID="Country1" runat="server" CssClass="form-control box-margin-8" Width="190px">
/--Here was very long list of countries so i removed--/
</asp:DropDownList>
</td>
</tr>
<tr>
<td class="">Email</td>
<td class="" style="text-align: inherit; font-family: 'Arial Black'; overflow: auto; width: 190px;">
<asp:TextBox ID="email" runat="server" CssClass="form-control box-margin-8" TextMode="Email" Width="190px"></asp:TextBox>
</td>
</tr>
<tr>
<td class="">Passport No</td>
<td class="" style="text-align: inherit; font-family: 'Arial Black'; overflow: auto; width: 190px;">
<asp:TextBox ID="passportNo" runat="server" Width="190px" CssClass="form-control box-margin-8"></asp:TextBox>
</td>
</tr>
<tr>
<td class="">Place of Issue</td>
<td class="" style="text-align: inherit; font-family: 'Arial Black'; overflow: auto; width: 190px;">
<asp:DropDownList ID="PlaceOfIssue" runat="server" CssClass="form-control box-margin-8" Width="190px">
<asp:ListItem Value="AF">Afghanistan</asp:ListItem>
/--Here was very long list of countries so i removed--/
</asp:DropDownList>
</td>
</tr>
<tr>
<td class="">Issue</td>
<td class="" style="text-align: inherit; font-family: 'Arial Black'; overflow: auto; width: 190px;">
<asp:TextBox ID="issue" runat="server" TextMode="Date" Width="190px" CssClass="form-control box-margin-8"></asp:TextBox>
</td>
</tr>
<tr>
<td class="">Expiry</td>
<td class="" style="text-align: inherit; font-family: 'Arial Black'; overflow: auto; width: 190px;">
<asp:TextBox ID="Expiry" runat="server" Width="190px" TextMode="Date" CssClass="form-control box-margin-8"></asp:TextBox>
</td>
</tr>
<tr>
<td class="">Visa No</td>
<td class="" style="text-align: inherit; font-family: 'Arial Black'; overflow: auto; width: 190px;">
<asp:TextBox ID="VisaNo" CssClass="form-control box-margin-8" runat="server" Width="190px"></asp:TextBox>
</td>
</tr>
<tr>
<td class="">Visa Expiry</td>
<td class="" style="text-align: inherit; font-family: 'Arial Black'; overflow: auto; width: 190px;">
<asp:TextBox ID="VisaExpiry" runat="server" Width="190px" TextMode="Date" CssClass="form-control box-margin-8"></asp:TextBox>
</td>
</tr>
<tr>
<td class="">Emirates ID No</td>
<td class="" style="text-align: inherit; font-family: 'Arial Black'; overflow: auto; width: 190px;">
<asp:TextBox ID="EmiratesNo" CssClass="form-control box-margin-8" runat="server" Width="190px"></asp:TextBox>
</td>
</tr>
<tr>
<td class="">ID Expiry</td>
<td class="" style="text-align: inherit; font-family: 'Arial Black'; overflow: auto; width: 190px;">
<asp:TextBox ID="EmiaratesExpiry" runat="server" Width="190px" TextMode="Date" CssClass="form-control box-margin-8"></asp:TextBox>
</td>
</tr>
<tr>
<td class=""> </td>
<td class="" style="text-align: inherit; font-family: 'Arial Black'; overflow: auto; width: 190px;"> </td>
</tr>
<tr>
<td class=""> </td>
<td class="" style="text-align: inherit; font-family: 'Arial Black'; overflow: auto; width: 190px;">
<asp:Button ID="submitt" runat="server" class="btn" OnClick="submitt_Click" Text="Submit" />
<input id="Reset1" type="button" value="reset" class="btn" onclick="myFunction()" />
<asp:Label ID="Label1" runat="server" />
<asp:Label ID="Label2" runat="server" />
</td>
</tr>
</table>
</div>
</div>
</div>
</div>
</div>
</asp:Content>
Here is the second page:-
<%# Page Language="C#" MasterPageFile="~/Site1.Master" AutoEventWireup="true" CodeBehind="DatabaseGView.aspx.cs" Inherits="Document_Expiry_Reminder.DatabaseGView" %>
<asp:Content ID="FormContentHolder" ContentPlaceHolderID="ContentPlaceHolder1" runat="server" >
<link href="css/bootstrap.css" rel="stylesheet" />
<div class="container">
<div class="img-responsive" style="background-color: none;">
<h1>
<img src="http://localhost:50090/uploads/icons/logo.png" style="height: 99px" /> Student Database Administration</h1>
</div>
<div class="row">
<div>
<hr />
</div>
</div>
<div class="displayflex">
<div class="row">
<div class="col-md-1">
<a href="FrontPage.aspx">
<img class="img-responsive" src="uploads/icons/add.png" /></a>
Add
</div>
</div>
</div>
</div>
<div class="row" style="margin-left: 5px">
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:Button ID="Button1" runat="server" Text="Search" OnClick="Button1_Click" /> <asp:DropDownList ID="DropDownList1" runat="server">
<asp:ListItem>Select Document</asp:ListItem>
<asp:ListItem>Passport Expiry</asp:ListItem>
<asp:ListItem>Visa & Emirates Expiry</asp:ListItem>
</asp:DropDownList>
From Date
<asp:TextBox ID="fromDate" runat="server" TextMode="Date"></asp:TextBox>
To Date
<asp:TextBox ID="toDate" runat="server" TextMode="Date"></asp:TextBox>
<asp:Button ID="Search" runat="server" OnClick="Search_Click" Text="Search" />
<br />
<br />
<asp:GridView ID="GridView1" runat="server" AllowSorting="True" AutoGenerateColumns="False" CellPadding="4" DataKeyNames="ID" DataSourceID="SqlDataSource1" OnRowEditing="GridView1_RowEditing" BackColor="White" BorderColor="#3366CC" BorderStyle="None" BorderWidth="1px">
<Columns>
<asp:CommandField ShowDeleteButton="True" ShowEditButton="True" ShowSelectButton="True" />
<asp:BoundField DataField="ID" HeaderText="Reg No" ReadOnly="True" SortExpression="ID" />
<asp:BoundField DataField="FN" HeaderText="First" SortExpression="FN" />
<asp:BoundField DataField="LN" HeaderText="Last" SortExpression="LN" />
<asp:BoundField DataField="Country1" HeaderText="Country" SortExpression="Country1" />
<asp:BoundField DataField="gender" HeaderText="Gender" SortExpression="gender" />
<asp:BoundField DataField="email" HeaderText="Email" SortExpression="email" />
<asp:BoundField DataField="PassportNo" HeaderText="Passport" SortExpression="PassportNo" />
<asp:BoundField DataField="PlaceOfIssue" HeaderText="Place Of Issue" SortExpression="PlaceOfIssue" />
<asp:BoundField DataField="Issue" HeaderText="Issue" SortExpression="Issue" DataFormatString="{0:MM/dd/yyyy}" />
<asp:BoundField DataField="Expiry" HeaderText="Expiry" SortExpression="Expiry" DataFormatString="{0:MM/dd/yyyy}" />
<asp:BoundField DataField="VisaNo" HeaderText="Visa" SortExpression="VisaNo" />
<asp:BoundField DataField="VisaExpiry" HeaderText="Visa Expiry" SortExpression="VisaExpiry" DataFormatString="{0:MM/dd/yyyy}" />
<asp:BoundField DataField="EmiratesNo" HeaderText="Emirates ID" SortExpression="EmiratesNo" />
<asp:BoundField DataField="EmiratesExpiry" HeaderText="ID Expiry" SortExpression="EmiratesExpiry" DataFormatString="{0:MM/dd/yyyy}" />
</Columns>
<EditRowStyle BackColor="Black" ForeColor="#0033CC" />
<FooterStyle BackColor="#99CCCC" ForeColor="#003399" />
<HeaderStyle BackColor="#003399" Font-Bold="True" ForeColor="#CCCCFF" BorderStyle="Groove" />
<PagerStyle CssClass="pagination-ys" BackColor="#99CCCC" ForeColor="#003399" HorizontalAlign="Left" />
<RowStyle BackColor="White" ForeColor="#003399" HorizontalAlign="Center" />
<SelectedRowStyle BackColor="#99CCFF" Font-Bold="True" ForeColor="#CCFF99" />
<SortedAscendingCellStyle BackColor="#EDF6F6" />
<SortedAscendingHeaderStyle BackColor="#0D4AC4" />
<SortedDescendingCellStyle BackColor="#D6DFDF" />
<SortedDescendingHeaderStyle BackColor="#002876" />
</asp:GridView>
<br />
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:SzabistStudentsConnectionString3 %>" DeleteCommand="DELETE FROM [Students] WHERE [ID] = #original_ID" InsertCommand="INSERT INTO [Students] ([ID], [FN], [LN], [Country1], [gender], [email], [PassportNo], [PlaceOfIssue], [Issue], [Expiry], [VisaNo], [VisaExpiry], [EmiratesNo], [EmiratesExpiry]) VALUES (#ID, #FN, #LN, #Country1, #gender, #email, #PassportNo, #PlaceOfIssue, #Issue, #Expiry, #VisaNo, #VisaExpiry, #EmiratesNo, #EmiratesExpiry)" SelectCommand="SELECT * FROM [Students]" UpdateCommand="UPDATE [Students] SET [FN] = #FN, [LN] = #LN, [Country1] = #Country1, [gender] = #gender, [email] = #email, [PassportNo] = #PassportNo, [PlaceOfIssue] = #PlaceOfIssue, [Issue] = #Issue, [Expiry] = #Expiry, [VisaNo] = #VisaNo, [VisaExpiry] = #VisaExpiry, [EmiratesNo] = #EmiratesNo, [EmiratesExpiry] = #EmiratesExpiry WHERE [ID] = #original_ID" OldValuesParameterFormatString="original_{0}">
<DeleteParameters>
<asp:Parameter Name="original_ID" Type="String" />
</DeleteParameters>
<InsertParameters>
<asp:Parameter Name="ID" Type="String" />
<asp:Parameter Name="FN" Type="String" />
<asp:Parameter Name="LN" Type="String" />
<asp:Parameter Name="Country1" Type="String" />
<asp:Parameter Name="gender" Type="String" />
<asp:Parameter Name="email" Type="String" />
<asp:Parameter Name="PassportNo" Type="String" />
<asp:Parameter Name="PlaceOfIssue" Type="String" />
<asp:Parameter DbType="Date" Name="Issue" />
<asp:Parameter DbType="Date" Name="Expiry" />
<asp:Parameter Name="VisaNo" Type="String" />
<asp:Parameter DbType="Date" Name="VisaExpiry" />
<asp:Parameter Name="EmiratesNo" Type="String" />
<asp:Parameter DbType="Date" Name="EmiratesExpiry" />
</InsertParameters>
<UpdateParameters>
<asp:Parameter Name="FN" Type="String" />
<asp:Parameter Name="LN" Type="String" />
<asp:Parameter Name="Country1" Type="String" />
<asp:Parameter Name="gender" Type="String" />
<asp:Parameter Name="email" Type="String" />
<asp:Parameter Name="PassportNo" Type="String" />
<asp:Parameter Name="PlaceOfIssue" Type="String" />
<asp:Parameter DbType="Date" Name="Issue" />
<asp:Parameter DbType="Date" Name="Expiry" />
<asp:Parameter Name="VisaNo" Type="String" />
<asp:Parameter DbType="Date" Name="VisaExpiry" />
<asp:Parameter Name="EmiratesNo" Type="String" />
<asp:Parameter DbType="Date" Name="EmiratesExpiry" />
<asp:Parameter Name="original_ID" Type="String" />
</UpdateParameters>
</asp:SqlDataSource>
</div>
</asp:Content>
From the second page, any click on link or button it redirects to fronpage.aspx which is firts page in my project

Check the form tag in master page, maybe it has action set to frontpage.aspx

Gridview Could not found control for modalpopupextender

I have a gridview with column "View" ID= "lnkViewContact". On click of this link signup modalpopupextender will be displayed. This popup is similar for all the rows. But when I am running it the error I am getting is "Could not found control lnkViewContact". How it can be resolved. one alternative is by using Onclick event on link click but I do not want to do a postback for opening the Popupextender. Below is my code:
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:Panel ID="pnlNoData" runat="server" align="center" Visible="false" Style="height: 300px;
width: auto;">
<h1 style="font-variant: normal; font-family: Times New Roman; font-size: 1.8em;
margin-left: 15px; font-weight: lighter; color: Green; margin-top: 100px;">
Refine your search.</h1>
<h1 style="font-variant: normal; font-family: Times New Roman; font-size: 1.8em;
margin-left: 15px; font-weight: lighter; color: Green; margin-left: 100px; margin-right: 100px;">
Not finding suitable candidates. </h1>
<cc1:ModalPopupExtender ID="mp3" runat="server" PopupControlID="pnlJobPost" BehaviorID="bvJobPost"
TargetControlID="lnkPostJobReq" BackgroundCssClass="mBackground" CancelControlID="btnClose">
</cc1:ModalPopupExtender>
<asp:LinkButton ID="lnkPostJobSignUp" Text="Sign Up and Post Job" Font-Size="Medium"
runat="server" OnClick="SignUp" Visible="false"></asp:LinkButton>
<asp:LinkButton ID="lnkPostJobReq" Text="Post Job Requirement" Font-Size="Medium"
runat="server"></asp:LinkButton>
</asp:Panel>
<asp:GridView ID="grdSearchResult" runat="server" DataKeyNames="SeekerEmail_Id, Extension"
OnRowDataBound="OnRowDataBound" AutoGenerateColumns="False" BorderWidth="1px"
BackColor="White" CellPadding="5" BorderStyle="None" BorderColor="Gray" GridLines="Both"
Width="100%">
<FooterStyle ForeColor="Black" BackColor="White"></FooterStyle>
<PagerStyle ForeColor="Black" HorizontalAlign="Center" BackColor="White"></PagerStyle>
<HeaderStyle ForeColor="White" Font-Bold="True" BackColor="Green"></HeaderStyle>
<Columns>
<asp:BoundField HeaderText="Job Skills" DataField="Primary_Skill" SortExpression="Primary_Skill"
ItemStyle-Width="35%" ItemStyle-HorizontalAlign="Center" ItemStyle-Wrap="true"
ItemStyle-CssClass="grdSearchResultbreakword"></asp:BoundField>
<asp:BoundField HeaderText="Resume Title" DataField="Resume_Title" SortExpression="Resume_Title"
ItemStyle-HorizontalAlign="Center" ItemStyle-Wrap="true" ItemStyle-Width="30%"
ItemStyle-CssClass="grdSearchResultbreakword"></asp:BoundField>
<asp:BoundField HeaderText="Exp (Years)" DataField="Experience" SortExpression="Experience"
ItemStyle-HorizontalAlign="Center"></asp:BoundField>
<asp:TemplateField HeaderText="Contact Details Email/Mobile" ItemStyle-HorizontalAlign="Center"
ItemStyle-Width="12%">
<ItemTemplate>
<asp:LinkButton ID="lnkViewContact" Text="View" runat="server"></asp:LinkButton>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Contact Details Email/Mobile" ItemStyle-HorizontalAlign="Center"
ItemStyle-Width="15%">
<ItemTemplate>
<asp:Label ID="lblContact" ForeColor="DarkOrange" runat="server" Text='<%# Eval("SeekerEmail_Id").ToString() +" / "+ Eval("Contact_Number").ToString() %>'
Style="word-wrap: normal; word-break: break-all; cursor: default;"></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Download Resume" ItemStyle-HorizontalAlign="Center">
<ItemTemplate>
<asp:LinkButton ID="lnkDown" Text="Download" runat="server" OnClick="SignUp"></asp:LinkButton>
</ItemTemplate>
</asp:TemplateField>
</Columns>
<SelectedRowStyle ForeColor="White" Font-Bold="True" BackColor="#008A8C"></SelectedRowStyle>
<RowStyle ForeColor="Black" BackColor="White"></RowStyle>
<SortedAscendingCellStyle BackColor="#F1F1F1" />
<SortedAscendingHeaderStyle BackColor="#0000A9" />
<SortedDescendingCellStyle BackColor="#CAC9C9" />
<SortedDescendingHeaderStyle BackColor="#000065" />
</asp:GridView>
<asp:LinkButton ID="lnkFake" runat="server"></asp:LinkButton>
<cc1:ModalPopupExtender ID="mp1" BehaviorID="behaviorIDmp1" runat="server" PopupControlID="Panl1"
TargetControlID="lnkViewContact" CancelControlID="btnCancel" DropShadow="true" BackgroundCssClass="modalBackground">
</cc1:ModalPopupExtender>
<asp:Panel ID="Panl1" runat="server" CssClass="modalPopup" align="center" Style="display: none;
height: 400px;" DefaultButton="btnRegister">
<%--<h1 style="font-variant: normal; font-family: Comic Sans MS; font-size: 1.5em; font-weight: lighter;
margin-top: 2px; margin-bottom: 2px; text-align: center; color: Blue;">
SIGN UP</h1>--%>
<asp:Label ID="lblEmailId" runat="server" ForeColor="Black" Text="Email address"
Style="font-weight: bold; display: block; text-align: left; margin-left: 45px;
margin-top: 10px;"></asp:Label>
<asp:TextBox ID="txtEmailAddress" runat="server" class="txtFirstName" MaxLength="100"
name="email" TabIndex="3" value="" /><br />
<asp:RequiredFieldValidator EnableClientScript="true" ID="reqEmailAdress" runat="server"
ValidationGroup="modal" ControlToValidate="txtEmailAddress" ErrorMessage="Email Address Required"
Display="Dynamic" Style="color: Red;" />
<asp:RegularExpressionValidator ID="regEmailAddress" runat="server" ErrorMessage="Not Valid Email ID"
ValidationGroup="modal" Display="Dynamic" ControlToValidate="txtEmailAddress"
ForeColor="Red" ValidationExpression="\w+([-+.']\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*">
</asp:RegularExpressionValidator>
<asp:Label ID="lblContactNumber" runat="server" ForeColor="Black" Text="Contact Number(Don't prefix 0 or +91)"
Style="font-weight: bold; display: block; text-align: left; margin-left: 45px;"></asp:Label>
<asp:TextBox ID="txtContactNumber" runat="server" class="txtFirstName" MaxLength="15"
name="contact" TabIndex="6" value="" /><br />
<asp:RequiredFieldValidator EnableClientScript="true" ID="reqContactNumber" runat="server"
ValidationGroup="modal" ControlToValidate="txtContactNumber" ErrorMessage="Contact Number Required"
Display="Dynamic" Style="color: Red;" />
<asp:RegularExpressionValidator ID="regContactNumber" runat="server" ControlToValidate="txtContactNumber"
ValidationGroup="modal" Text="Only 10 digit valid contact number is valid." ValidationExpression="[0-9]{10}"
Style="color: Red;" Display="Dynamic"></asp:RegularExpressionValidator>
<asp:Button ID="btnRegister" ValidationGroup="modal" class="btnempregsubmit" runat="server"
Text="Save" OnClick="Register" CausesValidation="false" />
<br />
<asp:HyperLink ID="btnCancel" runat="server" Text="Cancel" CssClass="btnClosePopup">Close</asp:HyperLink>
</asp:Panel>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="grdSearchResult" />
<asp:AsyncPostBackTrigger ControlID="btnRegister" />
</Triggers>
</asp:UpdatePanel>

It is a bit confusing when you mentioned 'one alternative is by using Onclick event on link click but I do not want to do a postback for opening the Popupextender. ' If you want an OnClick event, you will have to make postback. Below is a suggestion.
.....This part is your code....
<asp:LinkButton ID="lnkFake" runat="server"></asp:LinkButton>
<cc1:ModalPopupExtender ID="mp1" BehaviorID="behaviorIDmp1" runat="server" PopupControlID="Panl1"
TargetControlID="lnkViewContact" CancelControlID="btnCancel" DropShadow="true" BackgroundCssClass="modalBackground">
</cc1:ModalPopupExtender>
....Replace with this......
<asp:LinkButton ID="lnkFake" runat="server"></asp:LinkButton>
<cc1:ModalPopupExtender ID="mp1" BehaviorID="behaviorIDmp1" runat="server" PopupControlID="Panl1"
TargetControlID="lnkFake" CancelControlID="btnCancel" DropShadow="true" BackgroundCssClass="modalBackground">
</cc1:ModalPopupExtender>
And on the OnClick event code behind, do this to show the pop up
mp1.Show()

The Linkbutton inside a Gridview cannot be set as a TargetcontrolID of Modalpopupextender because at run time the ID of linkbutton will change dynaically. The work around is use the Onclick event of LinkButton and like in my case if there is any validation in modalpopupextender then validate the controls on server side.

Where to add BOLD Font?

Here we want to have Bold font for the facility name (data) i can't seem to able to make FONT added anywhere.
<Columns>
<dx:GridViewDataTextColumn FieldName="FACILITY_ID" Visible="false">
</dx:GridViewDataTextColumn>
<dx:GridViewDataTextColumn FieldName="Name" Caption="Facility Name" VisibleIndex="1">
<CellStyle HorizontalAlign="Left"></CellStyle>
<HeaderStyle HorizontalAlign="Center" />
<HeaderTemplate>
<div style="text-align: left; vertical-align: middle; float: left;">
<div style="float: left;">
<dx:ASPxImage runat="server" ID="imgFilter" ToolTip="Show/hide grid filter" ImageUrl="~/Content/Images/GridFilterButton.png">
<ClientSideEvents Click="ImageClick" />
</dx:ASPxImage>
</div>
<div style="float: left; padding-left: 10px; padding-top: 4px;">
Facility
</div>
</div>
</HeaderTemplate>

Set class="FacilityName" for your DataItemTemplate and apply styles for it
<dx:GridViewDataTextColumn FieldName="Name" Caption="Facility Name" VisibleIndex="1">
<DataItemTemplate>
<span class="FacilityName"><%# Container.Text %></span>
</DataItemTemplate>
</<dx:GridViewDataTextColumn>
css
.FacilityName
{
font-weight:bold;
}

coding is still showing the fieldname not the caption

In following code, I want to show not PATIENT NAME but "NAME" as it is in the caption
but it's still showing "PATIENT NAME". Is there another to use beside caption?
<Templates>
<DetailRow>
<dx:ASPxGridView ID="gvDetail" runat="server" ClientInstanceName="gvDetail"
AutoGenerateColumns="false"
DataSourceID="SqlDataSource1" Width="1100px" KeyFieldName="ID_KEY"
OnBeforePerformDataSelect="detailGrid_DataSelect" OnInit="gvDetail_Init">
<Columns>
<dx:GridViewDataTextColumn FieldName="ID_KEY" Visible="false">
</dx:GridViewDataTextColumn>
<dx:GridViewDataTextColumn FieldName="PATIENTNAME" Caption="Name" VisibleIndex="2">
<HeaderStyle HorizontalAlign="Center" />
<CellStyle HorizontalAlign="Left"></CellStyle>
<HeaderTemplate>
<div style="text-align: left; vertical-align: middle; float: left;">
<div style="float: left;">
<dx:ASPxImage runat="server" ID="imgFilterDetail" ToolTip="Show/hide grid filter" ImageUrl="~/Content/Images/GridFilterButton.png">
<ClientSideEvents Click="ImageClickDetail" />
</dx:ASPxImage>
</div>
<div style="float: left; padding-left: 10px; padding-top: 4px;">
Patient Name
</div>
</div>
</HeaderTemplate>