Edit 7/5/2015 It turns out this doesn't fix the problem. Attempting to play many of the songs that were previously corrupted ends up in them being corrupted again. It's easy to reproduce; just click the drop-down in the top right and select Songs to view your library in grid mode, then add the Date Modified column if it's not already there, sort by it, and try playing one of the songs with a date modified that corresponds to when you enabled iCloud Music Library. The song will revert to the incorrect album/artist. I'm guessing because the metadata in the file itself was jacked up by Apple, and when it's played the music library file that was restored earlier is updated to reflect the metadata in the file. Oh well. Here I am without a backup and a jacked up music library. Hopefully Apple will issue a fix soon. If you're like me and many others in that your iTunes Library was completely destroyed after enabling iCloud Music Library (albums renamed, albums duplicated, mixed up album artwork), you can fix it WITHOUT a Time Machine backup. I posted this in another thread but thought it would be worthy of its own thread so it could be sticky'd. Here's what my library looked like after enabling iCloud Music Library: Here are the steps to fix: - Close iTunes. - Navigate to your iTunes folder on your computer. You can find out which folder you're looking for from this Apple Support page. - Rename the "iTunes Library.itl" file to "iTunes Library_destroyed.itl" or "iTunes Library_AppleViolatedMe.itl" or whatever other name you'd like to use to get out your aggression. - Open the "Previous Libraries" subfolder. you'll see a bunch of "iTunes Library" files suffixed with dates. Pick the one that was created just before you turned on iCloud Music Library and copy and paste it into your iTunes folder library. - Rename the file you just pasted to "iTunes Library.itl". - Open iTunes. When it asks you to enable iCloud Music Library, DON'T DO IT! Your library should be back to normal. I guess Apple's screwed the pooch enough times after iTunes updates that they have a pretty decent backup system in place.