Bad Codec Problems Help

I recently downloaded and installed the lastest version of Ace Mega Codec Pack, of course after I uninstalled my old version of it.  Turned out it fixed the problem I was having with DVD playback in Windows Media Player, but here came the new problems.  EVERY AVI, MPEG, MPG, RM, WMV file as far as I know probably every video file type cannot be played now.  I try to run a file and all I get is the audio and a black screen.  I tried to fix this in multiple ways from uninstalling and reinstalling codec packs, old and new, uninstalling all codecs (as far as I can with control panel, that I know of), running Zoom Player and using its unregister codec feature, and some other programs called Sherlock 2.0 to find broken codecs, and Filter Manager.  I am seriously considering re-formatting, but the rest of my computer is fine and it would be a real hassle to have to re-install everything.  Does anyone know how I can go back to default codecs (basically wipe all but microsoft).  I even tried running system restore back to prior points, but all came back and said "Restore Incomplete" after rebooting.  Someone please HELP, I am desperate. :(  Video editing is my hobby and this totally messes everything up.