C# to give download link in gridview control

Source code fot gridview:-

   1:  <asp:GridView ID="grdsearch" runat="server" AutoGenerateColumns="False">

   2:                             

   3:<Columns>

   4: <asp:BoundField HeaderText="Full Name" DataField="FullName"/>

   5: <asp:BoundField HeaderText="Email ID" DataField="Email"/>

   6: <asp:BoundField HeaderText="Gender" DataField="Sex"/>

   7: <asp:BoundField HeaderText="Education" DataField="Education"/>

   8: <asp:BoundField HeaderText="Skills" DataField="Skillsetdetails"/>

   9: <asp:BoundField HeaderText="Total Experience" DataField="Totalexperience"/>

  10: <asp:BoundField HeaderText="Relvent Experience" DataField="Relventexperience"/>

  11: <asp:BoundField HeaderText="Address" DataField="Address"/>

  12: <asp:BoundField HeaderText="Previous Company Detail" DataField="Previousemployerdetail"/>

  13: <asp:BoundField HeaderText="Mobile Number" DataField="Mobileno"/>

  14: <asp:BoundField HeaderText="Availability" DataField="Availability"/>

  15: <asp:BoundField HeaderText="Currentctc" DataField="Currentctc"/>

  16: <asp:BoundField HeaderText="Expectedctc" DataField="Expectedctc"/>

  17: <asp:BoundField HeaderText="Preferred Location" DataField="StateName"/>

  18: <asp:BoundField HeaderText="Resume Name" DataField="ResumeName"/>

  19: <asp:TemplateField>

  20:  <ItemTemplate>

  21: <asp:LinkButton ID="LinkButton1" runat="server" Text="Resume Download" 

    CommandArgument='<%#Eval("Attachment")%>' OnCommand="btnDownload_Click">

  22:   

  23: asp:LinkButton>

  24:     ItemTemplate>

  25: asp:TemplateField>

  26:                  

  27:  Columns>

  28:  asp:GridView>

C# code to make file download on linkbutton click:-

 protected void btnDownload_Click(object sender, System.Web.UI.WebControls.CommandEventArgs e)
        {
            //Response.Write(e.CommandArgument.ToString());
            //Response.Write(e.CommandName.ToString()  );

            string queryString = e.CommandArgument.ToString();
            Response.Redirect(queryString);

        }