I found at http://ubuntuforums.org/showthread.php?t=1376466 the solution.
It appears that there is a issue in defining the keyboard layout when the UID of the user is 1000.
You must logout of your current session and login as root (if you didn't previously, before logout set a root password by running in terminal
sudo passwd root and follow the steps).
At login screen hit on the keyboard CTRL + ALT + F1.
Do login as root.
usermod -u 1001 your_user_name. 1001 is just a suggestion, you can put another.
Then reboot by typing
Hope it works!