Happy Saturday, Marlyn94!
It sounds like your Music app is crashing when you try to play a song. I know it's important to be able to play songs on your iPhone - I'm glad you came to the Apple Support Communities for help!
Use the guide below to fix this behavior:
If an app you installed unexpectedly quits, stops responding, or won’t open
Since the Music app isn't from the App Store, you won't be able to delete it as the article suggests. Instead, if you continue to experience this issue after following the above steps, use this guide to create a backup of your device:
How to back up your iPhone, iPad, and iPod touch
From there, restore your iPhone as this guide shows:
Use iTunes on your Mac or PC to restore your iPhone, iPad, or iPod to factory settings
Cheers!