It's a broken display profile. Photoshop is one of few applications that actually use the profile (color managed).
Recalibrate, or if you don't have a calibrator, use sRGB IEC61966-2.1. Go to Control Panel > Color Management > Devices:
Relaunch Photoshop so that it can pick up the new profile at startup.
awesome! did goto ctrl panel and add it in - restarted - colors back to normal! I was almost in panic mode and hoped my non tech description made sense, you nailed it for me. many thanks twenty_one, that was also super quick and i'm already back to some paintin'. I can now forward a couple other's I saw stuck to this thread - screenshot was nice too thanks again
You're welcome . This is actually a quite common problem. Many monitor/laptop manufacturers ship these bad profiles, and to make matters worse they come through Windows Update unless you stop them. That's likely how it hit you.