Just upgraded from 16.10 to 17.04 and when it restarted it went into plasma as expected but I wanted to check out unity 8 so I logged out and changed to unity. The screen went black. I tried restarting but I believe it logins to the last de by default so it kept going from the boot screen to a black screen.
I tried ctrl-alt-1 and got to the cli but now I still can't get back to plasma or anything else that works. sudo startx brings me to a black screen with a cross hair for a curser. Here I can access guake terminal emlutor but nothing else. I created a script early that restarts the plasma desktop on start up since it would need to be restarted whenever I shut my computer and opened it again. When I ran that in the emulator the plasma desktop comes up but I'm limited in what I can do. When I try to open most applications I get an error saying "could not find the program 'program-name'". And when I try to logout nothing happens.
I do have access to my file manager and settings though but haven't been able to find a solution using either of those. Changing default login settings isn't doing anything.
Any ideas how to get back to a normal session?