This happened to me yesterday. I was listening to music and it stopped, like a call was coming in, but nothing happened. I closed the music played and reopened it, nothing. Rebooted, nothing. Plugged it in to charge and it beeped, so I thought it was because it had a very low battery, but this morning we are back to silence again. It's only the loud speaker part, the normal speaker for phone calls still works. I haven't tried to play with the volume before but I tried N9 QTweak option S to confirm the volume, but only to put it at normal volume 67%. I haven't been tweaking my phone for a while (and to be honest, I only scratched the surface as far as tweaking goes!)and it's been really stable. This has come out of the blue and it would be criminal to have to buy another phone when I've been more than happy with this one. Hopefully someone can figure it out Cheers