Hi Debug,
I have checked your code and able to get the value also.
HTML
Masterpage
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<asp:ContentPlaceHolder ID="head" runat="server">
</asp:ContentPlaceHolder>
</head>
<body>
<form id="form1" runat="server">
<div>
<div id="all">
<div id="content">
<div class="container">
<asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
</asp:ContentPlaceHolder>
<div class="col-md-3">
<div class="panel panel-default sidebar-menu">
<div class="panel-heading">
<h3 class="panel-title">
Stay in touch</h3>
</div>
<div class="panel-body">
<div class="" id="details">
<div class="social">
<p>
<a href="https://facebook.com/mash" class="external facebook" data-animate-hover="pulse">
<i class="fa fa-facebook"></i></a><a href="https://twitter.com/mash" class="external twitter"
data-animate-hover="pulse"><i class="fa fa-twitter"></i></a><a href="https://www.instagram.com/mash"
class="instagram external" data-animate-hover="pulse"><i class="fa fa-instagram">
</i></a><a href="https://plus.google.com/mash" class="external gplus" data-animate-hover="pulse">
<i class="fa fa-google-plus"></i></a><a href="mailto:support@mash.com" class="email"
data-animate-hover="pulse"><i class="fa fa-envelope"></i></a>
<a href="https://linkedin.com/mash" class="linkedin external" data-animate-hover="pulse">
<i class="fa fa-linkedin-square"></i></a>
</p>
</div>
</div>
</div>
</div>
<div class="banner">
<a href="#">
<img src="../img/image1.jpg" alt="mash" class="img-responsive" />
</a>
</div>
<div class="banner">
<a href="#">
<img src="../img/image4.png" alt="mash" class="img-responsive" />
</a>
</div>
<div class="banner">
<a href="#">
<img src="../img/image3.jpg" alt="mash" class="img-responsive" />
</a>
</div>
</div>
<asp:ContentPlaceHolder ID="ContentPlaceHolder2" runat="server">
</asp:ContentPlaceHolder>
</div>
<!-- /.container -->
</div>
</div>
</div>
<div>
<!-- *** FOOTER ***-->
<div id="footer">
<div class="container">
<div class="row ">
<!-- /.col-md-3 -->
<div class="col-md-3 col-sm-6">
<h4>
User section</h4>
<hr />
<ul>
<li><a href="#" data-toggle="modal" data-target="#login-modal">Login</a> </li>
<li><a href="../Register.aspx">Register</a> </li>
</ul>
<hr class="hidden-md hidden-lg" />
</div>
<!-- /.col-md-3 -->
<div class="col-md-3 col-sm-6">
<h4>
Where to find us</h4>
<hr />
<p class="text-muted">
Please feel free to write an email to us.</p>
<ul>
<li><strong><a href="mailto:support@xyz.com">support@xyz.com</a></strong> </li>
</ul>
<a href="../Contactus.aspx">Go to contact page</a>
<hr class="hidden-md hidden-lg" />
</div>
<!-- /.col-md-3 -->
<div class="col-md-3 col-sm-6">
<h4>
Get the Latest Updates</h4>
<hr />
<p class="text-muted">
EmailID!</p>
<div class="input-group">
<input type="text" class="form-control" placeholder="your email address" id="emailID"
name="emailID" value="" />
<span class="input-group-btn">
<button class="btn btn-primary" id="submit" name="submit" runat="server" onserverclick="submit_click">
<i class=""></i>Subscribe!</button>
</span>
</div>
<!-- /input-group -->
</div>
<!-- /.col-md-3 -->
</div>
<!-- /.row -->
</div>
<!-- /.container -->
</div>
<!-- /#footer -->
<!-- *** FOOTER END *** -->
<!-- *** COPYRIGHT *** -->
<div id="copyright">
<div class="container">
<div class="col-md-6">
<p class="pull-left">
<a href="http:/Privacypolicy.aspx">Privacy Policy</a></p>
</div>
<div class="col-md-6">
<p class="pull-right">
© 2016 <a href="http://www.xyz.com">www.xyz.com</a> All rights reserved.<a href="#">
Designed by : Tang yuni.</a>
</p>
</div>
</div>
</div>
<!-- *** COPYRIGHT END *** -->
</div>
<script src="../js/front.js" type="text/javascript"></script>
</form>
</body>
</html>
Code
protected void Page_Load(object sender, EventArgs e)
{
}
protected void submit_click(object sender, EventArgs e)
{
string emailid = Request.Form["emailID"];
Response.Write(emailid);
//try
//{
// string qry = "sp_emailid";
// // TextBox tx = (TextBox)this.Master.FindControl("TextBox1");
// string emailid = Request.Form["emailID"];
// string date = DateTime.Now.ToString("yyyy/MM/dd hh:mm:ss");
// con = ConnectionManager.GetDatabaseConnection();
// SqlCommand cmd = new SqlCommand(qry, con);
// cmd.CommandType = CommandType.StoredProcedure;
// cmd.Parameters.AddWithValue("@EmailID", emailid);
// cmd.Parameters.AddWithValue("@Date ", date);
// cmd.Parameters.Add("@Error", SqlDbType.Char, 500);
// cmd.Parameters["@Error"].Direction = ParameterDirection.Output;
// cmd.ExecuteNonQuery();
// message = (string)cmd.Parameters["@Error"].Value;
// //Response.Redirect(Request.Url.AbsoluteUri);
// string script = "window.onload = function(){ alert('";
// script += message;
// script += "')};";
// Page.ClientScript.RegisterStartupScript(this.GetType(), "SuccessMessage", script, true);
//}
//catch (Exception ex)
//{
// string script = "window.onload = function(){ alert('";
// script += message;
// script += "')};";
// Page.ClientScript.RegisterStartupScript(this.GetType(), "FailureMessage", script, true);
//}
//finally
//{
// con.Close();
//}
}
Screenshot
