Brian, Don't give up. If you have a gui for the Guest account then there is a setting problem in your User account. Take a look via commandline as Sam suggests. Also use the older machine to review the Display manager vs. X window system vs Wayland. Wayland is the newer system and might be a change you didn't anticipate. Now the easiest way to access the files is to use a usb or pull the hard drive and use an adapter to attach it to your other machine. If you don't have the adapter go back to solving the original problem. Have you tried to add a new user with admin privileges. If that new user account has a gui, then you surely have an error in one of the config's saved in your original account. Keep in touch, there is always a solution. Thank you, Ted