Don't worry, the same happened to me recently I accidentally hit that combination of keys and ended up with the screen orientation wrong without knowing what keys I'd hit.
I tried everything I could think of. When my son came home from school he asked why I was working lying on the floor with the computer monitor on its side.
"This is all you have to do ........." he said. So simple when you know, so frustrating when you don't!
.. 'bout that beer ....... yep!