Possible Duplicate:
How to revert to GNOME Classic?
I recently installed Ubuntu 12.04, and it's with Gnome 3 and does not have classic menu like 10.04. Is there any way to have classic menu in 12.04 and any way to switch back and forth when I like to?
Reading state information... Done Package gnome-session-fallback is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source
E: Package 'gnome-session-fallback' has no installation candidate
– gmuhammad Aug 25 '12 at 10:06Universe
Repository is Disabled ,refer this image to enable it , runsudo apt-get update
and try installing it. – atenz Aug 25 '12 at 11:20