I'm running Ubuntu on an Averatec laptop with an external screen, installed via Wubi.

Ubuntu was working fine, then upon a certain reboot, the screen resolution became unusable. I can only see the top left portion of it, and lots is cut off. My desktop theme is no longer loading, desktop menu icons aren't loading, the maximize, minimize and close buttons on every window have disappeared, and everything generally tends to turn gray unless I move my mouse over it to refresh the text and icons. When I try to change the resolution to fit my screen, absolutely nothing happens.

This improper resolution has actually always occurred on this laptop during Ubuntu's splash screen and on the login screen, but it's always been corrected upon logging in (after I successfully changed the resolution on my first session). Any ideas of what could be the problem and how to fix it?