I'm new here, as of this morning, but I'm having similar troubles!! Only my screen turns sideways every time I wake it up from hibernation. Anyway, to turn it back to normal, just right click on your desk top and go to properties. Under the settings tab, click Advanced, and see if there is a Rotation tab.
Hope that helps! Someone just shared that with me this morning. Hope you don't have continued troubles with your monitor like I'm having!