I don't think you have the option of sending it back to Bandai for them to fix it. They just don't seem like the type to do repairs, they would probably recommend you get another one. Anyway, I'm a bit confused when you say your "buttons fell out." I mean, I get it, but the only way they can just fall out like that is if you had your Tamagotchi unscrewed almost all the way, at least, for them to fall cleanly out. Did you open your Tamagotchi recently? Did they fall cleanly out or did you break them off or what? If they fell out cleanly, just take apart your Tamagotchi and place the buttons back into the holes.