regedit

I have a puter that has sreved me well for some time. My wife was deleting some old non microsoft programs but had some trouble. She went into the registry and then.....now i cannot download files,view streaming videos,or even do windows update. I've tried many things and I am ready to do a reinstall of xp. My question is simply this. Will reinstalling xp change or affect any files backed up on my second hard drive in the system?