Im not sure how it died, but I have something you can try...I dont know if the baby will still be there or if it will work at all, but try restarting the tamagotchi and when the egg is there, I think to press the 'b' button, the middle one, and I think it gives you the option to download. Try downloading it back and see if they are still alive. Someone please correct me if Im wrong, lol, Im new at this, I just heard someone saying that that works sometimes.