It could be a bad inverter or burnt out gpu. First though, hook the laptop to the monitor again, let it boot up for a bit, then hit fn+f5 to see if it will kick the image over to the monitor. If it does, it is a bad inverter. If not, I suspect that something on the graphics chip burnt out. You can remove the hard drive and put it in an external enclosure ($30-$60 from say Best Buy) to get what you need off of it. If it is a newer laptop and you have a warranty, send it in.