Well... you have now really messed around with the registry too much, which means the solutions are not pleasant, unless you backed up the registry when you first played with it. Yes... I know, you didn't... or you wouldn't be here. (why do so many people skip simple safety steps like backups...? I'll never know...)
I would install ccleaner, and use it's registry cleaner. It's relatively benign and so is relatively safe. BUT BACKUP YOUR REGISTRY CHANGES when it offers to do so.
Reboot then try to reinstall zune. It may work, if so you are all set.
It may fail... if so, you are looking at a windows reinstall...
Note to everyone else: registry cleaners are generally smoke and mirrors. claims they will speed up your PC are 99.9% false (they may speed up boot up by a second or two, occasionally under the perfect circumstances. they also may remove keys incorrectly and muck up your pc badly. MS fixed the registry back in the old days prior to XP, and the need to 'clean' the registry disappeared, but not the folks trying to get you to buy or download their cleaners.)
Last edited by NSILMike; 05-26-2012 at 04:51 AM.