Well, as it will say in the beginning, when you open up your game, Villagers can die of stavation, sickness and plain old age. So if your villager was old or just getting up there in age, they tend to die off.

As far as your daughter is concerned. Well, kids can be so much better at this stuff than we are. But we have something over them. We, well, at least I did, had to dial a phone... WITH A ROTARY DIAL and we know what a record player was. Oh, I was supposed to be making you feel better, huh? lol... sorry...