I had this same issue and after some troubleshooting I realized that the left-side earphone control (the one that allows you to play/pause) was sticky. That is, it was 'stuck' in pressed mode, causing all other functions to fail (like the OP stated, charging still worked). So, there's a flakey solenoid (or something). My temp fix is to lightly tap the left earbud against something hard in the hopes that this action will dislodge it. To avoid having the button stick again, I've been controlling the audio via the iPhone controls (which sort of defeats the purpose of not having to retrieve the phone from one's pocket, but hey - one thing at a time).