string strFile = Server.MapPath("../UpLoad/IssueTrackingFiles/")+lbFileList.Items[item].Text;

                System.IO.FileInfo file = new System.IO.FileInfo(strFile);
                Response.Clear();
                Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(file.Name));

                Response.AddHeader("Content-Length", file.Length.ToString());
                Response.ContentType = "application/octet-stream";
                Response.WriteFile(file.FullName);
                Response.End();