[Wlug] Problem with usermod

Hi All, I'm running ubuntu (brezzy), and I just shot myself in the foot.... I went to add my username to a new group, but forgot to include the other groups that I belong to in the command. The command I used was 'sudo usermod -G <new-group> <my-username>'. Now I only belong to <new-group>. That removed my username from the other groups I belonged to, including the admin group. Is there a way undo what I did? I do have a copy of /etc/group before the change. Thanks, -Chuck