When I updated to 11.04 I changed the desktop to Gnome, now with the new 12.04 I'd like to switch back to Unity. How do I do this? Thanks!
I think it depends on how you switched it... Have you tried clicking the Ubuntu icon by the login name at the login screen, then switch it to "Ubuntu"? If you could explain how you "changed the desktop to Gnome" in the first place, maybe we could see about reversing that change.
Well... I guess this is a problem a lot of people is experiencing.
In my own case, I had customized compiz settings previous to the upgrade. And after upgrading from 11.10 to 12.04 compiz started to fail... hence no Unity, no launcher, no menu, no window frames... etc.
I assumed it was because of some personal compiz settings (although not sure which exact settings cause this), since I could login to the Guest account without problems, and there everything worked as expected.
So, I thought the only way to solve this was to reset compiz settings to defaults.
I believe this has already been asked. How can I switch between gnome-shell and unity without logging off?
Open a terminal and type:
just logout and select ubuntu on clicking setting icon and then login and you will have your unity environment set. Thats it.