pc question, Video card troubles :(

ok heres the story.
my uncles pc has had some seriously strange problems lately. and it seems every time we find a fix something else comes up to prevent the fix.

hes been haveing some video issues and his card doesnt show up in system/hardware/device manager at all.
so he tracks it down in display properties and I tell him to go ahead and disable it, big mistake, now no matter what video I am using (on board or the agp) windows loads normaly but when you get to the point where you should see a desktop its just blank screen.
I have tried toggling between on board and agp in set up but it has no effect. did I really just create a format/reinstall situation here?

any ideas would be appreciated.

Start up in Safe Mode and reinstall the drivers for the card. Do this by tapping F8 after the BIOS screen disappears and before the Windows splash screen comes up. Arrow down to Safe Mode and hit Enter. You will then be able to get into Device Manager or the Add New Hardware wizard.

This will work on any version of Windows later than NT4, but in the future it would be a good idea to mention what OS you’re asking about.

I forgot to mention the part about safemode locking up part way into the load…

Lets first start off with the type of system you have. OS, CPU, Video card model? If you have Windows 2000 or XP, you should be able to press F8 after the BIOS screen, don’t do safemode, instead select ‘Force VGA’, or something similar. It will load normally, but with basic VGA drivers, and a big, big screen. Goto where you disabled the driver, re-enable it. - This should bring back to normal, you can reboot now. Continue on to re-install drivers for the card:
After the previous step, now right-click and use the ‘Uninstall Drivers’ option. Before you do this, obtain the Driver CD, or Drivers from the manufacturers website. Reboot. Windows should come up saying it’s found new hardware. Depending on the instructions that come with the drivers, it will either tell you to skip the ‘found new hardware’ wizard for Windows and install the drivers with it’s own setup, or it will tell you where in the wizard you should point the location of the drivers (probably on CD or floppy). Hopefully this was helpful to you.

well I got the video goig again, f8 then enable vga, then before it booted up f8 again and use last settings that worked…I tried both of those independantly and had no luck…still cant find the damn card in the device manager inspite of the fact that I am running it . but at least I can see what the hell I am doing again, thanks for the help guys.