Is it possible that the camera has manual audio control which was previously on auto - or at a good manually set level - but is now set to 0 gain?
Is it possible that it has a mic jack and there is something plugged into that which bypasses the internal audio capture circuits?
Without a model number we have no way to tell...
What is different from the last time you recorded (successfully) and now?
Someone please help if you can. My Canon has no sound on playback after I record something. Using the same tape to play older things already recorded, the sound comes through fine. But new recordings are a problem. Could it be the mic? Could it be the tape? Is it recording souns at all? Could it need head cleaning, even though the video looks fine? Any asistance is greatly appreciated. Thanks!