My Music library in iTunes disappeared and can only retrieve music I purchased withing the past 12 month

Hi alysonfrommarlborough,

It sounds as though you're only seeing a small portion of what you expect to see when viewing your past purchases in iTunes. It may be that the purchases you have on an external hard drive were purchased under a different Apple ID. I've outlined below how to go about determining what Apple ID was used to make those purchases after they've been imported into iTunes.

1. Select a purchased song in your library.
2. Mac: From the menu bar at the top of your computer screen, choose File > Get Info.
   Windows: Press Control and B on your keyboard to turn on the iTunes menu bar. From the menu bar, choose File > Get Info. Learn more about menus in iTunes for Windows.
3. Click the File tab. Make note of the Account Name that appears in the list. This is the account name (Apple ID) that you need to use when you authorize your computer to play this purchase.
   The Apple ID that appears is the one that you used when you purchased the item. The Apple ID you used to purchase the item doesn't change, even if you change your Apple ID.

If iTunes repeatedly prompts you to authorize your computer - Apple Support

All my best

See also Empty/corrupt iTunes library after upgrade/crash.

tt2