English short story help!! plot and story line help PLEASE?

right, i've created a story for my A-Level coursework and i need to improve it, because quite frankly it's a load of crap.

i want to keep the same story line but change the plot a little because it's due in tomorrow! it needs to be 1500 words so i can't go in to too much detail!

right the plot is about a 10 year old orphan who has lived in a care home his whole life; the story starts with him getting abused by a care worker to which he is sent to his room. In hs room he begins to talk to his imaginary friend; a young peculiar child. His imaginary friend directs him out of the window and towards the forest outside the care home. Scared and confused the boy follows his imaginary friend only to get lost and fall over. Once he falls, he sees he has tripped over a dead body.. after much confusion he recognises the body belongs to his imaginary friend Andy to which he realises his imaginary friend is actually a ghost who was killed by the head care worker. After a care worker named John runs after the boy, he finds him standing next to the body. He calls the police, who find out that the care worker murdered Andy through forensic evidence, the care home is closed and the boy is adopted by John and lives happily ever after.

I just don't feel comfortable with this story, can anyone give me some suggestions to adjust the plot to make it more interesting.. maybe like a donnie darko plot, or something good becuase my teacher didn't particularly like it either..