So coworker of mine has been using a computer that I built him for a while now no problem with anything until just recently. While he was away from his computer his sister unplugged everything while it was on now no signal is being sent over to the monitor. Everything seems to be getting power and it turns on still. Any suggestions on how to fix this problem? If specs of the pc are need I can post that later once I figure out what was all used to make this build.