Public Sub GetFilePath(sender As Object, e As EventArgs)
        Try
            Dim iBtn As ImageButton = DirectCast(sender, ImageButton)
            ScriptManager.GetCurrent(Page).RegisterPostBackControl(iBtn)
            Dim item As RepeaterItem = CType(iBtn.NamingContainer, RepeaterItem)
            Dim fpath As Label = CType(item.FindControl("lblFilePath"), Label)
            If (fpath.Text <> "") Then
                f_FileName = fpath.Text
                f_FolderName = "~/ICT_ImpFiles/ClaimDocus/"
                Response.Redirect("~/DownloadImage.ashx?ImageName=" & "S_" & f_FileName & "&FolderName=" & f_FolderName)
            Else
                lblAlert.Text = "Sorry! There is no file found!"
                ScriptManager.RegisterStartupScript(Me, Me.[GetType](), "Pop", "showModal1();", True)
            End If
        Catch ex As Exception
            lblmessage.Text = "Er: " & ex.Message
            lblAlert.Text = ex.Message
            ScriptManager.RegisterStartupScript(Me, Me.[GetType](), "Pop", "showModal1();", True)
        End Try

    End Sub



DownloadImage.ashx



Imports System.Web
Imports System.Web.Services
Imports System

Public Class ShowImage
    Implements System.Web.IHttpHandler
    Dim file As String = ""
    Dim folders As String = ""
    Dim filename As String = ""
    Public Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest

        If (Not (context.Request.QueryString("ImageName")) Is Nothing) Then
            file = context.Request.QueryString("ImageName").ToString
        End If
        If (Not (context.Request.QueryString("ImageName")) Is Nothing) Then
            folders = context.Request.QueryString("FolderName").ToString
        End If
        filename = context.Server.MapPath(folders + file)
        Dim fileInfo As System.IO.FileInfo = New System.IO.FileInfo(filename)
        Try
            context.Response.Clear()
            context.Response.AddHeader("Content-Disposition", "attachment;filename=" + fileInfo.Name)
            context.Response.AddHeader("Content-Length", fileInfo.Length.ToString)
            context.Response.ContentType = "application/octet-stream"
            context.Response.TransmitFile(fileInfo.FullName)
            context.Response.Flush()
        Catch ex As Exception
            context.Response.ContentType = "text/plain"
            context.Response.Write(ex.Message)
        Finally
            context.Response.End()
        End Try

    End Sub

    ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable
        Get
            Return False
        End Get
    End Property

End Class