I think you're missing the OnCommand event capture because you have command name and command arguments but no event. Try something like this.
<asp:TemplateField ItemStyle-Width="50px" ItemStyle-HorizontalAlign="Center"> <ItemTemplate>
<asp:ImageButton ID="imgbtnUndo2" OnCommand="imgbtnUndo2_OnCommand" CommandName="Revert" runat="server" ToolTip="Undo" ImageUrl="~/Images/Undo.png" CommandArgument='<%# DataBinder.Eval(Container, "RowIndex") %>' />
</ItemTemplate> </asp:TemplateField>
You will need to handle the OnCommand event in codebehind for the image button to do anything, the handler should be named "imbtnUndo2_OnCommand" in this case.
PS: Code project removed all my capitals somehow, but hope this solves it.