[Solved] Download file from Path content is blank in ASP.Net

i am using this code to download file, but when file downloaded it is null it does not show any content where as when i open that file in the proejct folder it has content

in case of png it shows black screen

protected void dwnloadstl(object sender, EventArgs e)
{
    string filePath = (sender as Button).CommandArgument;
    Response.ContentType = ContentType;
    Response.AppendHeader("Content-Disposition", "attachment; filename=" + Path.GetFileName(filePath));
    Response.End();
}