takes the ImageUrl which is obtained from the dataset can help my

{
SqlConnection con = new SqlConnection();
    SqlCommand cmd = new SqlCommand();
    private SqlDbType sq;


    protected void Page_Load(object sender, EventArgs e)
    {


        if ("progimg "== "cmd")
        {
            string filename = " progimg".ToString();
            if (filename != "")
            {
                string path = MapPath(filename);
                byte[] bts = System.IO.File.ReadAllBytes(path);
                Response.Clear();
                Response.ClearHeaders();
                Response.AddHeader("Content-Type", "Application/octet-stream");
                Response.AddHeader("Content-Length", bts.Length.ToString());

                Response.AddHeader("Content-Disposition", "attachment;   filename=" + filename);

                Response.BinaryWrite(bts);

                Response.Flush();

                Response.End();
            }
        }