Startup
Ubuntu
Console
Ctrl, Alt, Function Key
Note: Don’t be surprised if the Gnome desktop is not be on Ctrl, Alt, F1 … it will probably be on: Ctrl, Alt, F7.
Stop the Display Manager
sudo /etc/init.d/gdm stop
Re-start the Display Manager
sudo /etc/init.d/gdm start
Re-start Desktop
Ctrl, Alt, Back-space.