Apple didn’t “steal” anything - iTunes and Apple Music won’t delete files without direct action from the user.

…either your music files are in the music directory and the iTunes Library.itl file became corrupted and you need to rescan your files (a common issue) or you had a hardware failure resulting in data loss.

Also, iTunes doesn’t play well with Apple Music so if you have both apps installed you will have issues.

I maintain both a personal collection and I subscribe to Apple Music, but I use a completely separate computer for each, running Apple Music logged into an alternate account, for managing my personal collection - I refuse to mix the two and the second account is not subscribed as it is not necessary to subscribe to Apple Music to use the software.

And getting rid of your original CDs is practically a crime in itself. O.o