Having problem with pre-installed game.

My son got a 3DS for christmas with Mario 2 pre-installed on it. (It is actually the red 3ds that has the Mario theme), it use to work fine, but now we cant find the Mario game in the home screen... Its been about a week, might someone uninstalled it if that is possible? is there a way to re-install it FREE? why cant we find the game? everything else is the same, we do recieve error on memory card message sometimes, but it is the same card that came with the system.