I looking for a movie about a boy who gets locked in the basement/cell by his mother, because his father left her. She keeps him in a cell and feeds him regularly by throwing or tossing the food to him. She dies and he's still lock in the cell. A family moves in and doesn't know he's in the there. I believe it's a family of a man, wife, son and a blind daughter.

Doesn't completely match, but it sounds very similar to Bad Ronald (http://www.imdb.com/title/tt0071186/).