For anyone working with Windows and it's inevitable updates I would recommend that you keep a copy of Nir Soft's "Produkey"
at hand. It saved me from buying a new copy of Win8.0 when the Windows Store update to Win8.1 trashed my install of Win8.0 because of a mix-up of product keys, replacement keys and semantics about "original" keys.
Produkey searched the trashed, unbootable, O\S when I slaved it to a Win7 install and returned with the actual keys that were used to activate the system. With those numbers I was able to reinstall Win8.0, including the Windows Media Center, download the upgrade ISO for Win8.1 and get up and running, without incident.
Produkey is included in Windows System Control Center, WSCC, which is a frontend for Nirsoft Utils, Sysinternal Utils, and Windows Utils.
Total of almost 300 essential utilities.
It was discussed here months ago but I think it come up in the world since that discussion. For one thing it now supports 64 bit systems.
Just search DC for wscc or Google will find it for you with just those four letters. It updates often. With so many utilities something is always being updated so punch the buttons for All Items and keep it current. It will get you out of trouble!
If not today, soon!
It will recover passwords too and password recovery utilities usually return as a virus in your AV program. You may have to whitelist them so they will be ignored on a virus scan.