10 villagers is more than the food supply can really support until your villagers have a more constant food supply. In the future, you can find out what happened while you were away by checking the game log immediately after you quit the game. The log is overwritten every time you start the game, however, so it must be examined right after you discover a problem. For more information about the game log, see the sticky post near the top of this forum.

There is a thread called Fan Guides to VV: The Lost Children in the Guide Section, which contains more detailed help, including a walkthrough.