Mazda Repair Questions? Ask Mechanics for Answers ASAP
If the radio still appears to function normally but has no sound, the amplifier has failed internally.
You'll need ro replace the radio assembly.
Sorry for bad news.
If you still have no sound at the moment, a jolt to the dash may make it work momentarily.
But more than likely, the head unit is faulty as I have mentioned above.
I hope my advice has been of assistance to you.