Before the problem started, I had run
sudo lightdm, which caused the system to hang. I hard rebooted, and then the problem began.
The system is Xubuntu 16.04.5.
Currently, I can log in via tty. I can get to the login screen. However, as soon as I log in via the [graphical] login screen, I get logged out. I am able to log in as another user, or as a guest user as well.
As stated here, I tried deleting the .Xauthority as well as .dmrc file to no avail.
I also tried reinstalling lightdm and xubuntu-desktop, to no avail.
Let me know if any more information is needed.