I just launched AF without my external hard drive connected. I closed AF, connected the drive and relaunched. All the sidebar groups I created which reference that drive have disappeared. I can't get them back. Restarting the computer did not help.
In the meantime could you please tell me the relevant file to backup so I can restore if need be. Also, will restoring this file replace any other settings I should know about? It's cost me enough time and I don't want to replace dozens of folders again. This is actually the second time I've them seen them disappear. The first time was a different cause. I chose disable AU's in preferences, selected relaunch and when AF opened they were gone.