Hey there, Mike!
Thanks for stopping by the Apple Support Communities. I understand from your post that you are unable to locate the Music app on your iPhone. I'm happy to help!
There are several reasons your Music app may be missing. First, it's possible it just got moved to another Home screen or into a folder. You can use the Search feature to try locating it on the device: Use Search on your iPhone, iPad, or iPod touch - Apple Support.
Another possibility is that restrictions have been enabled: Use parental controls on your child's iPhone, iPad, and iPod touch - Apple Support. If restrictions have been turned on, turning them off should restore access to the Music app.
The Music could potentially have been inadvertently removed from the phone, as well. If that's the case, you can redownload it from the App Store: Delete built-in Apple apps on your iOS 12, iOS 13, or iPadOS device or Apple Watch - Apple Support.
Cheers.