Apple has ‘stolen’ my music!

The "missing file" issue with exclamation marks happens if the file is no longer where iTunes or Music expects to find it. Possible causes are that you or some third party tool has moved, renamed or deleted the file, one of its parent folders, the drive it lives on has had a name change, or you've moved a non-portable library to a different path (see Make a split library portable for details). It is also possible that iTunes or Music have changed from expecting the files to be in the pre-iTunes 9 layout to post-iTunes 9 layout, or vice-versa, and so is looking in slightly the wrong place, or that you've been too aggressive when deleting duplicates at some point.

Select a track with an exclamation mark, use Cmd-I to get Song Info, then click No when asked to try to locate the track. Look on the file tab for the location the library thinks the file should be. Now take a look around your hard drives. Hopefully you can locate the track in question. If a section of your library has simply been moved, a folder renamed, or a drive label has changed, it should be possible to reverse the actions. If the difference between the two paths is an additional Music folder in one path then this is a layout issue. I can explain further if that is the case. If everything is where it is supposed to be try Repair security permissions for iTunes for Mac - Apple Community.

In some cases the library may be able to repair itself if you go through the same steps with Get Info, or when playing a track, but this time click Locate and browse to the lost track. It may then offer to attempt to automatically fix other broken links. Although it says something like "use the same location" I think it expects to find the tracks in the same artist & album layout they were in previously, with one systematic change to the path.

If you want me to try to provide specific advice please post back the following details:

1. The location of the media folder under iTunes|Music > Preferences > Advanced
2. The location of a sample missing track shown under Song Info > File > Location that begins file://
3. The true path to the file whose details you gave in 2

See also FixLinks - an AppleScript to repair broken links in Music - Apple Community.

tt2

This is a user to user support forum. I have no access to any case you might have with Apple Support. I do have some experience helping people repair damaged iTunes libraries however. Are you able to use Spotlight on your Mac to locate the file 02 Loser.m4a and if so what is the path to it?

As you have a not yet closed Apple Music subscription there is the potential to redownload some media from the cloud, however that might replace your lossless content with 256K AAC versions, and only works for content that was matched or uploaded. so relinking the library to your original files would be the preferred approach.

When you say you have a backup on external drive is this a clone of an earlier state of your iTunes folder, or have you moved content to an external drive to free space not realising it might impact the library? If you cannot find that particular track in local storage now copying back from the external drive to the path indicated above - <User's Music>/Music/Media/3 Doors Down/The Better Life - would repair that particular link, and indicates the general approach you would need to use to restore other songs.

tt2

What is the exact text of any error message you get when you try to 'access' any of this content?

What did you do between the last time your content worked properly and the start of this behaviour?

Is your media on the iPhone from where it could potentially be recovered if you have no other form of backup?

Do you subscribe to either Apple Music or iTunes Match?

tt2

No worries, that is helpful. Can you locate the file 02 Loser.m4a and if so what is the path to it?

tt2