Once or twice a year we get a call from someone frustrated that without warning everything on his screen is now upside-down or rotated 90 degrees. Rebooting didn’t fix it. Neither did plugging in a different monitor. Help!
This is caused by accidentally pushing a reserved keyboard short cut. This one is designed to let you rotate your monitor 90 degrees so you can type in portrait mode. Or if you have the monitor flat on the desk you might want to rotate it completely upside-down to show to someone sitting opposite.
So what’s the fix?
If you do want to rotate your screen, use CTRL-ALT ←, CTRL-ALT-→ or CTRL-ALT-↓
Annoy your friends, amuse your enemies!