Alienware M15x Resolution?

My boyfriend's computer got a virus and he tried to fix it, but it made the situation worse. It seems like everything has been erased off of it except for 11 programs, primarily Cisco stuff. I'm not exactly sure what to do to fix that at this point, and perhaps it's a little nit-picky but the screen resolution is off. How do I reset the screen resolution to 1600x900? I tried going through the display tabs but it doesn't go that high.