It sounds like something happened to your video driver. I'd go to Device Manager and right-click the video driver, and have it revert to the previous one. Did you by chance opt to load a new one via Windows Update? That could explain what's happened because getting drivers from other than the manufacturer has been known to cause this kind of thing.
The day began ok, the usual Windows updates were found at 3am, and then Windows asked if i would like to restart to apply the updates, so I did, as usual. Restart seemed to take a long time, and when all the noise stopped, the monitor screen was black. The light on the monitor was orange, I wiggled the mouse, nothing. Usually this is where it turns green light and then everything is fine. Not fine today! I tried restart a few times, same deal. Then I found to go to Safe Mode, did that, type in run Msconfig ok then Boot.ini was chosen. then BaseVideo then reboot! It worked, everything shows up, except its in 8bit and a pop up saying resolution is very low. If I go to Properties and change it, and hit apply it restarts and then I get the black monitor. But as long as I go to safe mode, and do the above, the entire monitor shows everything on my PC. Whats wrong? I ran diagnostic and it says its all good, also tried to update the Radeon drivers but it says I have the latest. Anyone have any ideas? I only use this to do emails and play old games like Age of Empires and Diablo (the old versions that run on XP) but it works and it runs super fast and now it does nothing except piss me off with the black screen. Any help would be greatly appreciated!