I have the same problem as in this question but the solution mentioned here (removing Xauthority and autostart) does not solve the problem.
This problem is: I now have a log in screen which I did not have before and I dont know the password. (The problem likely started b/c of an autoremove after some problems with installing Lamp)
So I reset the password (grub -> recovery -> root) after remounting. But after rebooting, the newly set password for user is not accepted at login!
So the initial problem still exist: login screen which I don't want and I can not log in
I am Using 16.04.
Struggling with it for some hours now. Does anyone know how to fix this?
Additional Observation 1 altered text: I noticed what seemed two different root dirs. As pointed out below this has nothing to do with the problem
Aditional Observation 2: in my last session in which I was still able to work in Ubuntu, the cursor started to behave strangly as it had will of it's own. That's why I rebooted resulting in above situation
Additional Observation 3 I can not log in as Guest either. I get this error message: "Failed to start session"