My guess is the sound wire broke or came off. Open up the tamagotchi and look at the two wires. If they are not connected from the circuit board to the speakers then that is the problem and it is sorta an easy fix, as long as you have a soldering Iron. It they are both there then something must have broken off of the circuit board. One way to figure this out is if you open it and find there is any loose pieces(besides the buttons or pieces that are supposed to be loose(Screen, those pink things normally attached to the screen, sometimes they fall off, the background, or that odd square thing next to the background, and of course the buttons). Before you open it shake it if you hear clunking noises you out of luck it means there is a loose piece I don't really know how to fix a loose piece but the sound wires is easy. If you need help with any part of it PM me. (Also you you solder the wires into the wrong slots that means the sound wont work)