Hello there, adi.
It sounds like when you play music, the repeat setting is turned on for what you play. The following link to the online iPhone User Guide provides the instruction on how to change the repeat setting:
Play music - iPhone
Control playback. Tap a song to play it and show the Miniplayer. Tap the Miniplayer to show the Now Playing screen, where you can do the following:
Skip to any point in a song. Drag the playhead. Decrease the scrubbing speed by sliding your finger down the screen.
Share music. Tap , then choose a sharing option.
Shuffle. Tap to play your songs in random order.
Repeat. Tap to repeat an album or playlist. Double-tap to repeat a single song.
If you find the issue persists, although this article was written for third-party apps you install on your iOS device, the first set of steps are useful for troubleshooting the Music app, in this case:
If an app you installed unexpectedly quits, stops responding, or won’t open - Apple Support
Close the app and open it again.
Turn your device off and back on.
- Make sure that you're using latest version of iOS.
- Open the App Store and tap Updates.
- If updates are available, tap Update All.
- If asked, enter your Apple ID password.
You might need a Wi-Fi connection to update some apps.
Thanks for being a part of Apple Support Communities.
Kind Regards.