Well, there are several things you can try. First, boot into Safe Mode, and change your display settings to VGA. (Yes, you're already at VGA, but you want to change it so it will be viewable when you restart Windows.) So choose 640 X 480 and 16 colors and then hit Apply. Then try restarting normally and see if you get your screen back.
Chances are that you've lost your video driver or it's been corrupted, which explains the X in Device Manager. In Safe Mode, you're using a standard video driver and your card's drivers aren't being used. When your system crashed, it may have upset your settings somehow.
If it works, and you can see the screen, then you should be able to install your video drivers. If it does start, it'll be just like Safe Mode. If you try to change the resolution, it might work, but it more likely won't without new drivers and you'll be back where you started.
So the next step is finding out where your motherboard drivers are. If they're standard Windows drivers, you can get them either from the Windows CD or from the CAB files if you've copied them to your hard drive. (Always a good idea.) But if it's a specialty card or onboard graphics, you may need to get them from a driver disk that came with the card, the motherboard disk (if it's onboard), or the manufacturer's driver CD. If you don't have any one of those options, you may need to look for the drivers online at the manufacturer's site.
If you don't know what your video card is, you may have to crack the case. You could use software like this older Everest Home
to find out what it is.