How sexist of you..you only want help from the guys, eh?!?
Well I'm a man..so I guess I can chime in..
Make sure the cables are secure first and formost..I had this problem and it took me forever to figure it out, because I never thought that could be the problem since my computer doesn't move. Computers are the devil though, and may unplug accessories from itself, so you should check to be sure!