all my music ended up on my husband's iPhone and all his music disappeared. how can we retrieve it?

Hello 4maximus,

We would like to see how we can help you with your music. Are you both sharing the same Apple ID? Are you a part of a Family Sharing plan? Check out the steps in this link and get back to us with your results: Use Sync Library to access your music library across your devices

"How to turn on Sync Library on your iPhone or iPad

1. Make sure that your iPhone or iPad is signed in with the same Apple ID that you use with your Apple Music subscription.
2. Go to Settings.
3. Tap Music.
4. Turn on Sync Library.
5. 
6. Turn on Sync Library on your other devices."

Cheers!