Car Electronics Questions? Ask an Electronics Expert for Answers ASAP
Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
It sounds as if the amplifier in the stereo that drives the speaker has been damaged by the battery running down. That is esp. likely if it was On (at any time) or connected to the power, while the battery ran down, since undervoltaging is almost as harmful and overvoltaging.
(Does the stereo have a headphone jack or earphone jack? double-check my impression by listening to it for a little by that means.)
For an amplifier with a blown-out component or several (which is what your problem distinctly and definitely sounds like, to me), you cannot reset the issue and make it go away that way.
The stereo will need repair - or, if there is an accessory amplifier driven by it, between it and the speakers, the amplifier will need repair.