Wally, I know it's a hassle and a half, but considering all the issues plaguing your computer, I think a clean install is the best way to go. Even if you could somehow get into Windows and do a Repair Install, there's no guarantee that something won't be left behind that could corrupt things again. Clean Install Windows 7 Clean Install with a Upgrade Windows 7 Version
A couple of other suggestions ... and I offer them as someone who's been there, done that, and got the T-shirt. After you get your 7 reinstalled and it's time to get the Windows Updates, I'd install SP1 first. That will incorporate a bunch of pre-SP1 patches, hotfixes, etc. I'd get SP1 from the Microsoft Download Center
and not rely on Windows Updates.
After SP1 installs use Windows Updates for the remaining 2,561 patches, hotfixes, etc. (It will seem like that many if you follow my suggestion.) Install just a few at a time - maybe 5 or so. After each group is installed, play around with the computer for a bit to make sure there are no problems. Then install the next 5. If you do discover a problem you've narrowed it down to one of 5 updates.
After you have everything set up again, I would strongly urge you to make a system image on an external hard drive. Yeah, it's gonna cost some $$$ but once you have a system image, if you ever experience a major computer meltdown again, you can be up and running in 30 minutes or less. Update the image every week or so (or when you make a major system change create two images - a before and after) and you'll never have to go through this hassle again.
I'm really sorry I couldn't be more help.