First off, before you delve into the barely-complicated-but-scary-if-you-don't-understand-it stuff: Assuming you have CAS parts (Clothing, hair, makeup, etc) just open the game and go into CAS (the small button to the left of the play button) and check for it.
The only way it'll hurt your saves is if you load a save, then save it again with the CC gone, thus making the game forget the CC was there.
If the extension of the files is still .package, it won't hurt anything. It probably just changed the default program they open with, which doesn't affect the game loading them at all.
To check the extension:
http://i.imgur.com/MUpyR1E.png
Source: Microsoft - I assume if I were to direct-link that, this would need to be approved.
If you have W8 and don't have a third-party start menu, roll over the right side of the screen > click Settings > then Control Panel.
If the CC still doesn't work:
It's probably as easy as just changing the extension. They don't actually get opened with anything. They're just files that the game reads when it's loaded.
To change the extension, just right-click > Rename (or select the file and hit F2) and delete the extension after the . and replace it with package.
