Most masturbation happens because of habit. You introduce it as a habit and then it becomes hard as fuck to remove it.
I stopped when I went for a month to a country house. I'm not saying that you should move, only that the massive change in environment completely removed my habits (as I had not associated any habits with that place).
After some time without following them the habits go away.
Most of the time masturbation is asociated with a certain moment, a certain image (i.e. laying in your bed at nightime looking at some place).
What I recomend you do is rearange your room, to break the environment and the habits associated with it. If you can, move (temporarily) to another house, preferably to one in which you can't form masturbation habits (e.g. living and or sleeping with other people).
I did this about three months ago, and since I've lost all urges to masturbate, even if I still get horny every once in a while (I suppose that is healthy, being an eunuch is not the objective). The first days I still had urges to masturbate, but they went away.