If the hotkey solution does not work, I suggest that you actually rotate the monitor (so that you can read it), right-click on empty screen area and select the Properties option in the menu that will appear, go to the Settings tab, select your monitor, and look for a Rotation setting.
On my personal machine, I have to go into the Control Center installed by the video driver package.
For the people who still come here for answers,on windows 7 the hot keys are ctrl / alt and up arrow. the arrow tells it where the top of the screen should be. I don't think this works on most desktop, for them you need to use control panel