How to increment/decrement download counter in asp.net 3.5?

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C#

ASP.NET

Javascript

In my project the facility to download some file to the user but there is only the 3 times any user download same file, for that i m using one counter. So when user download file the counter is decremented by 1 & when counter reaches to zero the download of these particular file is not allowed to the user.for these I use gridview
all are well performed counter is decremented,but the problem is that the decremented counter is not shown in grid.so, how to show it.
My Code is-

<asp:GridView ID="gdvOrderDetails" runat="server" AutoGenerateColumns="False"
        Width="977px" onrowdatabound="gdvOrderDetails_RowDataBound">
        <Columns>
            <asp:TemplateField HeaderText="Serial No">
                <ItemTemplate>
                    <asp:Label ID="gdvlblserialno" runat="server"></asp:Label>
                    <asp:Label ID="lblProductType" Visible="false" Text='<%# Eval("ProductType") %>' runat="server"></asp:Label>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Date">
                <ItemTemplate>
                    <asp:Label ID="gdvlbldate" runat="server"></asp:Label>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Themes">
                <ItemTemplate>
                    <asp:ImageButton ID="gdvimgbtndownload" runat="server"
                        ImageUrl="../_img/icons/download-now-short.png"
                        CommandArgument='<%# Eval("ProductId") %>' onclick="gdvimgbtndownload_Click"/>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Downloads Remaining">
                <ItemTemplate>

                    <asp:Label ID="gdvlbldownloadcount" runat="server"></asp:Label>

                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Downloads Valid Till Date">
                <ItemTemplate>
                    <asp:Label ID="gdvlbldwnvalidtildt" runat="server"></asp:Label>
                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
    </asp:GridView>

& the code for download

 public bool identify(string filenm)
        {
            //string filePath = "D:\\Rakesh\\DLLNEW\\testDll\\dllManaged";
            //string filePath = "C:\\Webroot\\product.dgflick.com\\updates";
            string filePath = Server.MapPath("~/upload/templates/book-xpress/");
            //string str2 = "C:\\FileZilla2\\data";
            //string _DownloadableProductFileName = "Bx-Pro-Update-3.0.exe";
            string _DownloadableProductFileName = filenm;
            System.IO.FileInfo FileName = new System.IO.FileInfo(filePath + "\\" + _DownloadableProductFileName);
            FileStream myFile = new FileStream(filePath + "\\" + _DownloadableProductFileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
            BinaryReader _BinaryReader = new BinaryReader(myFile);
            if (FileName.Exists)
            {
                //try
                //{
                long startBytes = 0;
                string lastUpdateTiemStamp = File.GetLastWriteTimeUtc(filePath).ToString("r");
                string _EncodedData = HttpUtility.UrlEncode(_DownloadableProductFileName, Encoding.UTF8) + lastUpdateTiemStamp;
                Response.Clear();
                Response.Buffer = false;
                Response.AddHeader("Accept-Ranges", "bytes");
                Response.AppendHeader("ETag", "\"" + _EncodedData + "\"");
                Response.AppendHeader("Last-Modified", lastUpdateTiemStamp);
                Response.ContentType = "application/octet-stream";
                Response.AddHeader("Content-Disposition", "attachment;filename=" + FileName.Name);
                Response.AddHeader("Content-Length", (FileName.Length - startBytes).ToString());
                Response.AddHeader("Connection", "Keep-Alive");
                // Response.End();
                
                Response.ContentEncoding = Encoding.UTF8;
                _BinaryReader.BaseStream.Seek(startBytes, SeekOrigin.Begin);
                maxCount = (int)Math.Ceiling((FileName.Length - startBytes + 0.0) / 1024);
                for (i = 0; i < maxCount && Response.IsClientConnected; i++)
                {
                    Response.BinaryWrite(_BinaryReader.ReadBytes(1024));
                    Response.Flush();
                }
                if (i < maxCount)
                {
                    return false;
                }
                if (i == maxCount)
                {
                    if (Response.IsClientConnected == true)
                    {
                        return true;
                    }
                    else
                    {
                        return false;
                    }
                }
                _BinaryReader.Close();
                myFile.Close();
                //if blocks transfered not equals total number of blocks
                //}
                //catch
                //{
                //    return false;
                //}
                //finally
                //{

                //    //Response.End();
                //    _BinaryReader.Close();
                //    myFile.Close();
                //}
            }
            return false;
        }

& the download is perform on these button which is in gridview-
protected void imgBtnDownload_Click(object sender, ImageClickEventArgs e)
        {
            
            string prodId = ((ImageButton)sender).CommandArgument.ToString();
            GridViewRow row = (GridViewRow)((Control)sender).Parent.Parent;
            int index = row.DataItemIndex;
            Label lblDownloadCount = (Label)gdvOrderDetails.Rows[index].FindControl("lblDownloadCount");
            Label lblExpiryDate = (Label)gdvOrderDetails.Rows[index].FindControl("lblExpiryDate");
            Label lblExDate = (Label)gdvOrderDetails.Rows[index].FindControl("lblExDate");
            Label lblProductName = (Label)gdvOrderDetails.Rows[index].FindControl("lblProductName");
            Label lblImgUrl = (Label)gdvOrderDetails.Rows[index].FindControl("lblImgUrl");
            string imgUrl = lblImgUrl.Text;
            string prodName = lblProductName.Text;
            string todaysDate = DateTime.Now.Date.ToShortDateString();
            DateTime today = Convert.ToDateTime(todaysDate);
            DateTime exDate = Convert.ToDateTime(lblExDate.Text);
            if (DateTime.Now.Date <= exDate.Date)
            {
                int downloadCount = Convert.ToInt32(lblDownloadCount.Text);
                if (downloadCount > 0)
                {
                    int lastFolderIndex = imgUrl.LastIndexOf("/");
                    string folders = imgUrl.Substring(0, lastFolderIndex + 1);
                    folders = folders.Replace("galleria/book-xpress/thumbnail", "templates/book-xpress");
                    //Response.Redirect(folders + lblProductName.Text + ".exe");
                    bool res = identify(lblProductName.Text + ".exe");
                    if (res == true)
                    {
                    clsDownload objUpdateCount = new clsDownload();
                    objUpdateCount.strOrderNo = lblOrderNo.Text;
                    objUpdateCount.strProductId = prodId;
                    clsDownload.UpdateDownloadCount(objUpdateCount);
                    //lblDownloadCount.Text = Convert.ToString(downloadCount - 1); 
                    //Response.AddHeader("Refresh","0;URL=Index.aspx"); 
                    //Response.AddHeader "Refresh", "0;URL=default.asp"
                    Response.Headers.Clear();
                        Response.Redirect(Request.RawUrl);
                      
                    //Page.ClientScript.RegisterStartupScript(this.GetType(), "", "<script type='text/javascript'>windows.location.reload();</script>");
                    //LoadGrid();
                    }
                
               }
                else
                {
                    clsJava.MessageBox("Sorry, Your download count reached to 0. You can not download.");
                }
                }
                else
                {
                    clsJava.MessageBox("Sorry, Your downloads are expired. You can not download.");
                }
         }

the rowdatabound event of gridview-
protected void gdvOrderDetails_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                string ordno = DataBinder.Eval(e.Row.DataItem, "OrderNo").ToString();
                string exDate = DataBinder.Eval(e.Row.DataItem, "ExDate").ToString();
                string dwn = DataBinder.Eval(e.Row.DataItem, "DownloadCount").ToString();
                string productType = DataBinder.Eval(e.Row.DataItem, "ProductType1").ToString();
                ImageButton imgBtnDownload = (ImageButton)e.Row.FindControl("imgBtnDownload");
                string todaysDate = DateTime.Now.Date.ToShortDateString();
                DateTime today = Convert.ToDateTime(todaysDate);
                DateTime expDate = Convert.ToDateTime(exDate);
                Label lblDownloadCount = (Label)e.Row.FindControl("lblDownloadCount");
                lblDownloadCount.Text = dwn; 
                if (DateTime.Now.Date > expDate.Date)
                {
                    lblDownloadCount.Text = "0";
                }
                if (productType == "2")
                {
                    imgBtnDownload.Visible = true;
                    lblDownloadCount.Visible = true;
                }
                else
                {
                    //TemplateControl tempContol =(TemplateControl)gdvOrderDetails.TemplateControl.FindControl("Downloads Remaining");
                    //tempContol.Visible = false;
                    imgBtnDownload.Visible = false;
                    lblDownloadCount.Visible = false;
                }
            }
        }

the Load Grid function which is load the grid-
 public void LoadGrid()
        {
            string orderNo = "DFSPL11289"; // clsQueryString.OrderNo.ToString();
            lblOrderNo.Text = orderNo;
            //string orderNo = "DFSPL11278";
            clsDownload objProductDownloads = new clsDownload();
            objProductDownloads.strOrderNo = orderNo;
            DataTable dtProductDownloads = clsDownload.GetAllProductDownloads(objProductDownloads);
            if (dtProductDownloads.Rows.Count > 0)
            {
                gdvOrderDetails.DataSource = dtProductDownloads;
                gdvOrderDetails.DataBind();
            }
        }