Q: how do i resolve sound problem

Hi mela_rbr,

I understand that your iPhone appears to be changing the volume on you when you're listening to music. In such a situation, it may help to force close all open apps, then restart your iPhone.

Force an app to close in iOS
http://support.apple.com/en-us/HT5137

Turn your iOS device off and on (restart) and reset
http://support.apple.com/en-us/HT1430

If your iPhone continues to fail to control its volume, the next step would be to reinstall iOS on your device by placing it in Recovery Mode, then choosing Update in iTunes. Prior to doing so, it's always a good idea to make sure that you've got a backup made.

1. Make sure that you have iTunes 12 or later on your computer.
2. Put your device in recovery mode.
3. When you get the option to restore or update, select Update. This will reinstall iOS without erasing your data.

If your iPhone, iPad, or iPod touch doesn't respond or doesn't turn on
https://support.apple.com/en-us/HT201412

Cheers!