use this template field in your gridview
<asp:gridview id="grdAdd" runat="server" autogeneratecolumns="false" xmlns:asp="#unknown">
<columns>
<asp:TemplateField HeaderText="SrNo."> <ItemTemplate> <%#Container.DataItemIndex+1%> </ItemTemplate>
<ItemStyle Width="8%" /> </asp:TemplateField>
</asp:gridview>
if your problem will soved please accept my answer