I would recommended going to see blackberry Tech to help you fix or replace your volume keys, or if your running any apps see if there is volume keys that can turn volume up or down
These are the settings I know when it comes to your phone:;
Adjust the volume To increase the volume, press the Volume Up key on the right-hand side of your BlackBerry® smartphone. To decrease the volume, press the Volume Down key on the right-hand side of your smartphone. To mute the volume, press the Mute key on the right-hand side of your smartphone. To turn off mute, press the Mute key again. If you press the Mute key during a call, your smartphone mutes the call so that you can hear others on the call, but they can't hear you.
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