I once rotated the screen on my Dell laptop by accident and couldn't figured out how to get it back to normal. Took almost a day.

By right-clicking the document, and seeing "Rotate clockwise" and "Rotate counterclockwise" in the context menu, along with their corresponding shortcuts?

That's actually a good example of a traditional UI that is designed around a few basic patterns (right click -> context menu, here) that enable discoverability.