I am trying to lose weight and i train 5 times per week for 3 to 4 hours and i am on diet but i ain't losing any weight?

Balance: Weight loss results from energy expended > energy taken in. You say you're on a diet but, have you restricted your calories too much? The body needs enough fuel to work or it won't drop weight. Check the timing of your meals as well. Consider getting the advice of a nutritionist to help with that. As for the exercise, make it varied so your body doesn't become accustomed to it. Best of luck.