Its about a woman who has a young boy and the boy gets hit by a car (whilst his mum is shopping) and the boys dies and his mum knows a doctor who brings the boy back to life and the boy keeps having nightmares of his past and at the end he is sitting at the top of a hut in a forest and he is going to kill his mother?? Can't think of the movie name!! SOMEONE HELP ME THANKS?! :)

Sounds like Godsend (2004) with greg kinear and Robert De Niro. The doctor clones the boy who was killed.
Hope this helped.