Hello and welcome to Apple Support Communities, Ira R..
If we understand your post correctly, the Music app on your Mac sometimes has no sound until you quit the app and relaunch it. We’d like to help.
First, try these resets:
How to reset the SMC of your Mac
Reset NVRAM or PRAM on your Mac
If this issue continues after those resets, let's do some testing to narrow down the issue.
Safe mode will tell us if the issue is related to a startup item or plugins, and sometimes corrects the issue. This article will tell you how: How to use safe mode on your Mac
If everything is working correctly in safe mode, but is not working when you get back to your user account, please check the section titled "If the issue doesn't continue in safe mode" for the next troubleshooting steps.
Thanks for using the Apple Support Communities. Take care.