Photoshop screen is tracking off the bottom of my computer scree--how do I get it back?

Hello,

The bottom 1/2 inch of my photoshop screen has slid off the bottom of my computer screen, and now I cant grab either of the lower corners of the photoshop screen or see the bottom of my rulers, which is frustrating. Im sure this is an easy fix buy I cant seem to figure it out. Thanks for the help!