Comment 4 for bug 1292396

Looking at DpkgLog.txt file it looks like a whole slew of packages, including the all-important ubuntu-desktop metapackage, were removed on 2014-03-13 around 23h00. It's not clear why these packages were removed, but all the unity-2d packages were removed and compiz was not, which is a little odd considering the unity2d are dummy packages on which nothing should be depending.

I would recommend trying to fix your packages by explicitly installing the unity-desktop package and see if it fixes your current problems.