How can I retrieve Apple Music on my iPhone?

Your Apple Music app disappeared, or the contents of your Apple Music library, or your Apple Music subscription?

If this is the app that has disappeared, first check if the app was deleted:

Remove or delete apps from iPhone - Apple Support

Next, turn off Screen Time, Focus, and Parental Controls (if enabled), and check again.

If this is your Music, first see if force-restart your iPhone reconnects to Apple Musid:

Force restart iPhone - Apple Support

If this is a missing subscription, confirm you are using the same Apple Account, or are part of Family Sharing with an Apple Account that has Apple Music Family Plan, then check with Apple Support.

What do you mean by "Apple Music"? Do you mean the Apple music app was removed from a Home Screen or Deleted entirely from the iPhone?

Is the App there but your actual music library is now missing, ie, the Apple Music app is empty?

Are you referring to an Apple Music subscription? Was it cancelled?

Something else?

What exactly is missing or can't you do?

Please explain in as much detail as possible what happened. Remember we cannot see what you see.