Cannot 'locate' original file / song

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

Hey there, JolaRouge!

Welcome to Apple Support Communities! We're happy to have you here, and we'd be happy to look into helping you locate those songs. You mentioned that you've worked with Apple already to determine where they may be located. In Change where your music files are stored on Mac - Apple Support, were you able to follow:

Locate your Music files

1.In the Music app  on your Mac, click Songs in the sidebar on the left.

2.Do one of the following:

Find out where a file is stored: Select the item, then choose Song > Info.

The path to the file is shown at the bottom of the File pane (next to location).

Show the file in the Finder: Select the item, then choose File > Show in Finder.

If you don’t see Show in Finder, the file may be in your music library and not on your computer.

If so, when you look at the path of the file, then navigate to the folder, what do you see? For example, does the folder appear to not contain any information?

If you're unable to locate anything in those folders, have you recently made any changes to your Mac? Do you have a backup of the data on your Mac, such as Time Machine?

Additionally, are the songs that are missing ones that were ripped from CDs, or were they all purchased using iTunes or added using Apple Music?

We look forward to hearing back from you.

Take care!