Request for technical assistance

Cats are amazingly savvy with computers. I've had the cat step on my keyboard and open up applications I didn't know my computer had. Scheherazade stepped on Superman's keyboard earlier this evening and managed to turn his screen display sideways. Does anyone know how to turn it right? He has searched for a solution online with no success. He's pushed every key combination he thinks might help, to no avail. Help!

Update: Thanks to Lewis' timely direction and useful links, the problem is solved. Lewis is Superman's Hero of the Day.