Q: Apple Music in Vietnam

Hello Justfordawin,

Thank you for being part of the Apple Community!

It is my understanding you are experiencing an issue using Apple Music.  With all the great music available on Apple Music, I can certainly understand wanting to be able to access it.

The first thing I would recommend would be to force quit the music app:

Force an app to close on your iPhone, iPad, or iPod touch

If the issue continues after restarting the App, then shutting off and restarting the iPhone would be the next step: 

Restart your iPhone, iPad, or iPod touch

Test again and if the problem continues, you want to make sure you have a current backup of everything on your iPhone. If you follow this link, you will find instructions on how to do a backup: 

How to back up your devices using iCloud or iTunes.

Once the backup is finished, I would reset all settings. 

Reset All Settings resets preference files that may be having issues. This step will not delete your contacts or photos or any personal information. It does remove all of your preferences for Wi-Fi, Bluetooth, Do No Disturb, Notifications, General, Sounds, Brightness & Wallpaper and Privacy, and removes your Touch ID & Passcode.

You do this by tapping Settings > General > Reset > Reset All Settings. 

Have a great day!