[WebMethod]
        public void download(string filename)
        {
            string conn = @"Data Source=.;Initial Catalog=sql;Integrated Security=True";
            string str = "select FileByte from TestFile where FileName=filename ";
            string path = "c://"+filename;            
            SqlConnection myconn = new SqlConnection(conn);
            SqlDataAdapter sda = new SqlDataAdapter(str, conn);
            DataSet myds = new DataSet();
            myconn.Open();
            sda.Fill(myds);
            myconn.Close();
            Byte[] Files = (Byte[])myds.Tables[0].Rows[0]["FileByte"];

            BinaryWriter bw = new BinaryWriter(File.Open(path, FileMode.OpenOrCreate));
            bw.Write(Files);
            bw.Close();

        }