Strangely broken monitor?!

So, I have an old Sony laptop (Windows XP), and it's broken and I'm completely lost on how to fix it. I've really never seen anything like it. When I turn it on, everything is working just fine, except for the monitor. The monitor won't light up, and it's black, YET, if I shine a light on it I can see the desktop. It's as if it still has the monitor but it's lost all of it's brightness. I tried turning up the brightness, but to no avail. I troubleshooted it, and it couldn't find anything wrong. Has anybody in recorded history ever experienced something like this, and if so, how do I fix it?!