Re: Majority of CC missing from Mods folder after updating.

@muffinsnbuttons  Normally when Sims 4 user data (saves, mods, etc.) disappears, the first place to look is a cloud storage service: OneDrive for Windows, iCloud for macOS.  But the usual presentation is that everything disappears, or else all the newer content disappears and much older saves show up instead.  Still, you can check OneDrive for any missing Sims 4 files; maybe you'll get lucky.

You can also search your hard drive for the files.  Open a File Explorer window, click This PC in the left panel, and enter *.package (with the asterisk) in the search box.  This should turn up any .package files on your hard drive.  If you see the missing files, click on one of them, click "Open file location," and you'll land wherever the files went.  From there you can move them back to their proper place.

This kind of thing shouldn't happen, but sometimes it does, and not always for reasons that can be explained.  The only good way to prevent it is to keep a backup copy of the Sims 4 user folder, or at least the essential files within it, so you can restore them in the event they disappear.