Hi muhammad12,
Please refer below code.
HTML
<link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" />
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datetimepicker/4.17.37/css/bootstrap-datetimepicker.css" />
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script type="text/javascript" src="http://maxcdn.bootstrapcdn.com/bootstrap3.3.7/js/bootstrap.min.js"></script>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.9.0/moment-with-locales.js"></script>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datetimepicker/4.17.37/js/bootstrap-datetimepicker.min.js"></script>
<div class="form-group" style="margin: 30px">
<div class='input-group date' style="width: 200px">
<asp:TextBox ID="txtTime" runat="server" CssClass="form-control" />
<span class="input-group-addon"><span class="glyphicon glyphicon-time"></span></span>
</div>
<br />
<asp:Button ID="btnSubmit" Text="Submit" runat="server" OnClick="OnSubmit" />
</div>
<script type="text/javascript">
$(function () {
$('[id*=txtTime]').datetimepicker({
format: 'LT'
});
});
</script>
Code
protected void OnSubmit(object sender, EventArgs e)
{
DateTime time = DateTime.Parse(Request.Form[txtTime.UniqueID]);
}
Screenshot