When updating itunes it lost music
Apple makes no representations regarding third-party website accuracy or reliability. It’s a common problem you may meet after you upgrade your i Tunes to a new version.
Depending on the version of i Tunes that you have, there are different ways to update.
i Tunes 12.2 with support for Apple Music came out yesterday and managed to create quite a stir for all the wrong reasons.
Some of us updated to the new version only to find our existing i Tunes library ridden with missing tracks and exclamation marks.
If you can’t update to mac OS 10.14 Mojave, you might still be able to get some updates for i Tunes (up to i Tunes 12.8).
Open the App Store on your Mac, then click Updates at the top of the App Store window.