Today I finally resolved a problem I had for a while on one of my computers.

When logging in using the normal lightdm X11 login screen, directly on the computer, I would get an error and absolutely no menu, no icons, no keyboard functionality, no unity, no nautilus... The only thing I had working was the background which gave me access to the settings, but nothing else. More or less, nothing useful.

I just had an idea and then I found a comment form a user on a forum who said that he just deleted his .config and .compiz directories and rebooted. After that it worked for him. It worked for me too!

If you'd like to save your old settings, copy them first, then restart lightdm (you do not need to fully reboot.) Note that I had access via SSH so I did this in a console from another computer. But I also had access to other accounts, so either way I could have run those commands.

mv .compiz old-compiz
mv .config old-config
sudo service lightdm restart

After that, try to log back in your account and everything should be back.

Source: http://forum.parallels.com/threads/ubuntu-14-04-no-gui-after-login.30108... (search for reply with CTRL-ALT-FN-1)