try
        {

            string PathDownloadImage = ConfigurationManager.AppSettings.Get("PathDownloadImage").ToString();

            // string filename = this.Page.Request.QueryString["FileName"].ToString();

            int buffersize = 1;

            string fileThumbName = "";

            if (Request.QueryString["fileThumbName"] != null)
            {
                fileThumbName = Request.QueryString["fileThumbName"].ToString();
            }

            HttpWebRequest objRequest = (HttpWebRequest)WebRequest.Create(PathDownloadImage + fileThumbName);
            HttpWebResponse objResponse = (HttpWebResponse)objRequest.GetResponse();


           // System.IO.FileInfo targetFile = new System.IO.FileInfo(fileThumbName);



            string fullFilePath = Server.MapPath( "Wallpapers/Thumb/" + fileThumbName); //might be you need to change this statement if file does not exist within application folders

            System.IO.FileInfo fileInfo = new System.IO.FileInfo(fullFilePath);

            Response.Clear();

            Response.AddHeader("Content-Disposition", "attachment; filename=" + fileInfo.Name);
            Response.AddHeader("Content-Length", fileInfo.Length.ToString());
            Response.ContentType = "application/download";
            //Response.TransmitFile(fileInfo.FullName);
            Response.BinaryWrite(File.ReadAllBytes(fileInfo.FullName));

            Response.Flush();
            //Response.Close();
            Response.End();






            //Response.Clear();
            //Response.ContentType = "application/download";
            //Response.AppendHeader("Content-Disposition", ("attachment; filename=" + targetFile.Name));
            //Response.AppendHeader("Content-Length", objResponse.ContentLength.ToString());

            //byte[] byteBuffer = new byte[buffersize + 1];
            //MemoryStream memStrm = new MemoryStream(byteBuffer, true);
            //Stream strm = objRequest.GetResponse().GetResponseStream();
            //byte[] bytes = new byte[buffersize + 1];

            //while (strm.Read(byteBuffer, 0, byteBuffer.Length) > 0)
            //{
            //    Response.BinaryWrite(memStrm.ToArray());
            //    Response.Flush();
            //}

            //Response.Close();
            //Response.End();
            //memStrm.Close();
            //memStrm.Dispose();
            //strm.Dispose();
        }
        catch (Exception ex)
        {
            ex.Message.ToString();
        }