Don't ever, ever, ever offer to repair a corrupted Windows system. I've lost my bony arse removing a problem and having fifteen others arise.
OTOH, I have turned a few easy 100 dollar jobs offering to save documents and pictures, wiping/reinstalling Windows, and reinstalling software. Thanks to a USB hard drive interface and a Linux home PC, I usually get the whole job done in an hour or two (while I'm multitsasking).
Never,ever try to fix a sick Windows system. You'll get filthy, and it annoys the pig.