How can i lose wieght?

I am 19, 5 ft 6 and weigh 170lbs. When i was 13 i weighd 164lbs and felt depressed, when i was 16 i weightd 134lbs from doing martial arts and felt great about myself. But i could aford to stay in it. Now with all the weight gain i feel so depressed again. I have tryd everything i could think of like walkin/jogging work out videos, danceing, youtube workout video, healthy eating, but its like the weight wont come off. I really want to lose 50lbs by next summer, plzzzx help.