Got a laptop with a broken screen. I had to reboot because of virus. How do I get my external monitor to work?

The screen of my laptop got broken so I connected my external monitor to it. After that I managed to get a virus that completely ****** my computer up, so I just rebooted it. Problem is that I can barely see the screen (although I can see it if I focus really hard on it) and when I try using the typical Fn-F4 key, it dosn't come on anymore. I've also tried start + P, but dosn't work either. Is it because of missing software/drivers?? What can I do to make it work again (I know for a fact that it is the laptop, not the monitor that dosn't connect). The laptop is an Hp elitebook 8530p.