I'm trying not to make a duplicate of a previous question, but I do have the same problem. I'm using gdm3 and have purged, and reinstalled multiple times. A different user 'test' and sudo startx work. So it seems to be a config issue, but I'm unsure. I've exhausted everything save reinstalling Ubuntu.
After following this question, I am stumped as to what to do because I'm not seeing the same files. I'm looking at the following section:
"move some of the common configuration files out of the way:"
mv ~/.config ~/.config.old --moved
mv ~/.local ~/.local.old --moved
mv ~/.cache ~/.cache.old --moved
mv ~/.nvidia-settings-rc ~/.nvidia-settings-rc.old --not found
mv ~/.nv ~/.nv.old -- not found
sudo systemctl reboot
This didn't resolve my problem, and I want to believe that this can solve it, but I haven't figured it out. I'm going to purge gdm3 once more and reboot before reinstalling.
I have fresh installs of nvidia drivers, and again. I can get a desktop to show up, but not for my user account.