How to download a file in asp.net c# linkbutton

aspx

 string filePath = (sender as LinkButton).CommandArgument;

            Response.ContentType = ContentType;

            Response.AppendHeader("Content-Disposition", "attachment; filename=" + Path.GetFileName(filePath));

            Response.WriteFile(filePath);

            Response.End();

aspx.cs

<asp:LinkButton ID="lnkDownload" runat="server" CausesValidation="False" CommandArgument='<%# Eval("DocumentFilePath") %>'

                                                                            CommandName="Download" OnClick="lnkDownload_Click" Text='<%# Eval("DocumentFilePath") %>' />

or

if (e.CommandName == "Download")

            {

                string filePath = "~\\cbisupportfiles\\Rent\\" + "Hindi.pdf";

                //string filePath = "~//cbisupportfiles//Rent//" + "Roles05232018052335.txt";

                if (!string.IsNullOrEmpty(filePath))

                {                   

                    string filename = "Hindi.pdf";

                    string Filpath = Server.MapPath("~/cbisupportfiles/Rent/" + filename);

                    DownLoad(Filpath);

                   

                }

public void DownLoad(string FName)

        {

            string path = FName;

            System.IO.FileInfo file = new System.IO.FileInfo(path);

            if (file.Exists)

            {

                Response.Clear(); //Clear all the response that we have written above this line(Response.write)

                Response.AddHeader("Content-Disposition", "attachment; filename=" + file.Name); Response.AddHeader("Content-Length", file.Length.ToString());

                Response.ContentType = "application/octet-stream"; // download […]

                Response.WriteFile(path);

                Response.End();// Response will end here and no html tags or html code will be write in file if it is txt file otherwise it will add html code that is generated by asp.net automatically

            }

        }