[Quiet Man Cometh]

Probably a bum speaker or bum wire. I had a pair of headphones that would glitch on me like that. Twisting the plug around a bit sometimes corrected it. Same thing with speakers that plug into the headphone jack. On occasion one out of a pair might quit, but we are talking $10 speakers.

That might be a brief fix for you if you can find a pair. I had one for my CD player that plugged into the headphone jack and they worked for a laptop as well. Not the best sound in the world but it might get you both speakers back. I had them because my desktop monitor had no speakers at all.