"Unable to load session 'ubuntu'" in 12.04

Question

I removed Unity via the Software Store and rebooted.

Now I got the following error:

unable to load session 'ubuntu'

I can't log in as guest either.

Answer 1

Repair attempt:

Please open tty (virtual console, text mode only): Ctrl+Alt+F1

Enter:

sudo apt-get update
sudo apt-get install ubuntu-desktop
sudo apt-get -f install
sudo dpkg-reconfigure ubuntu-desktop
sudo reboot

If above does not work, try:

sudo apt-get install gnome-session
sudo apt-get install lightdm
sudo apt-get install unity-greeter
sudo dpkg-reconfigure lightdm

The install commands will tell self-explanatory if it’s already installed or not.

Credits: http://riveridea.wordpress.com/2012/03/22/how-to-solve-failed-to-load-session-ubuntu/

Answer 2

Because the problem is unable to load session 'ubuntu', So the solution might

sudo apt-get install ubuntu-session