Hmmm... well this has happened to my friend before, but hers came back. If it did not turn into an angel or make a dramatic exit, then the batteries need changing. Peace, Applegurl
Just like Bubbles11 said, it probebly ran out of battery power. or your tamagotchi is very delicate because you tried to debug it ,or take off the back and you hit your tama on somthing somtimes your charcter will disapear