I had the same problem.
I tried with
unity --reset (as it used to fix things when I messed things up before with compiz-config) but that didn't solve my problem now.
The only thing I could do for getting everything working as normal was to reset compiz settings.
Just backup (rename)
~/.config/compiz-1 directories and let them to be created again with the default settings (you'll need to logout and log back in again).
mv ~/.compiz-1 ~/.compiz-1.BACKUP mv ~/.config/compiz-1 ~/.config/compiz-1.BACKUP
After having restarted and confirmed that everything works as expected, you can simply remove these backups (unless you have a use for them).
rm -Rfv ~/.compiz-1.BACKUP rm -Rfv ~/.config/compiz-1.BACKUP
Note: To some people, one of the following links might have the solution. Try them if you don't want to lose all your compiz customizations.
- http://askubuntu.com/questions/17381/unity-doesnt-load-no-launcher-no-dash-appearsUnity doesn't load, no Launcher, no Dash appears
- http://askubuntu.com/questions/17610/how-do-i-reset-my-unity-configurationHow do I reset my Unity configuration?
In my case just resetting Unity wasn't enough, so I decided to get rid of all compiz settings.