protected void grdStudentDetails_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
       grdStudentDetails.PageIndex = e.NewPageIndex;
       grdStudentDetails.DataBind();
    }

<asp:GridView ID="grdStudentDetails" runat="server" AllowPaging="True" AutoGenerateColumns="True" CellPadding="4" DataKeyNames="Studentid" Font-Size="Medium" ForeColor="#333333" GridLines="None" OnRowDataBound="grdStudentDetails_RowDataBound" HorizontalAlign="Center" PageSize="10" Visible="true" onselectedindexchanged="grdStudentDetails_SelectedIndexChanged" onpageindexchanging="grdStudentDetails_PageIndexChanging">