Well..I've found out the following.
The last update affected to Secure Boot. It made propietary drivers not to work anymore (they are not signed) so one of the things I made through command line was to uninstall them and reinstall XOrg.
sudo apt-get purge "fglrx.*"
sudo apt-get install --reinstall xserver-xorg-core
Probably the resintallation of XOrg affected to the following (I'm not sure)
The owner of the file .Xathority was root and not my user so that was the reason because it was stuck in that part.
I made the following:
sudo chown myusername:myusername .Xauthority
And the system is working again properly.
P.S. Thanks gsekse for trying to help.