Open Modal Popup on Button click with different Title and Body using C# and VB.Net in ASP.Net

Hi sani.ss501,

Refer below sample.

HTML

<script type="text/javascript" src='https://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.8.3.min.js'></script>
<script type="text/javascript" src='https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.0.3/js/bootstrap.min.js'></script>
<link rel="stylesheet" href='https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.0.3/css/bootstrap.min.css'
    media="screen" />
<script type="text/javascript">
    function ShowPopup(title, body) {
        $("#MyPopup .modal-title").html(title);
        $("#MyPopup .modal-body").html(body);
        $("#MyPopup").modal("show");
    }
</script>
<center>
    <asp:Button ID="btnShowPopup" runat="server" Text="Show Popup" OnClick="Show" CssClass="btn btn-info btn-lg" />
    <asp:Button ID="Button1" runat="server" Text="Display Popup" OnClick="Display" CssClass="btn btn-info btn-lg" />
</center>
<!-- Bootstrap -->
<!-- Bootstrap -->
<!-- Modal Popup -->
<div id="MyPopup" class="modal fade" role="dialog">
    <div class="modal-dialog">
        <!-- Modal content-->
        <div class="modal-content">
            <div class="modal-header">
                <button type="button" class="close" data-dismiss="modal">
                    &times;</button>
                <h4 class="modal-title">
                </h4>
            </div>
            <div class="modal-body">
            </div>
            <div class="modal-footer">
                <button type="button" class="btn btn-danger" data-dismiss="modal">
                    Close</button>
            </div>
        </div>
    </div>
</div>

Code

C#

protected void Show(object sender, EventArgs e)
{
    showPopup("Greetings", "Welcome to ASPSnippets.com");
}

private void showPopup(string title, string body)
{
    ClientScript.RegisterStartupScript(this.GetType(), "Popup", "ShowPopup('" + title + "', '" + body + "');", true);
}

protected void Display(object sender, EventArgs e)
{
    showPopup("Hey", "Guys !");
}

VB.Net

Protected Sub Show(ByVal sender As Object, ByVal e As EventArgs)
        showPopup("Greetings", "Welcome to ASPSnippets.com")
    End Sub

    Private Sub showPopup(ByVal title As String, ByVal body As String)
        ClientScript.RegisterStartupScript(Me.GetType(), "Popup", "ShowPopup('" & title & "', '" & body & "');", True)
    End Sub

    Protected Sub Display(ByVal sender As Object, ByVal e As EventArgs)
        showPopup("Hey", "Guys !")
End Sub

Screenshot