How do you fix Xauthority?
Change the Permissions of Xauthority
Instead of root, your user and group should own that Xauthority file. You can change the ownership by running the chown command with sudo. That should go off without a hitch, so you're ready to try logging in again. Press Ctrl + Alt + F7 to return to your normal login screen.
How do I get to the login screen in Ubuntu?
If you do get to a prompt (try 'ctrl+alt+F1' or 'ctrl+alt+F2', the GUI is usually on ctrl+alt+F7) you could try and start the login screen with sudo service lightdm start . If this does work you may have a different problem, maybe installing the display manager again will fix any errors.
What causes login loops?
Login loop is an issue when you log-in to your system and it takes back you to the login screen again, instead of letting you use the desktop and this process repeats indefinitely. ... This happens because of some irrelevant changes to the files in your system caused by the display manager.