I've tried Macbuntu, but did not quite like it, so I uninstalled it but Ubuntu didn't restore completely.
There are now only close, minimize, maximize buttons in Panel, while originally there should be other application menu options like "file, edit, view, help etc...", which disappeared now.
It looks like this:
I've tried reset Unity by
unity --reset
but it does not work.
I'm using Ubuntu Desktop 12.04.