What do you suggest if i want to lose 20 kgs(44lbs) in 6 months, but don't know how ?

Consider working w a: nutritionist & /or trainer. Eat healthfully. Try to eat at least 5 servings of vegetables & 4 of fruit per day. Increase nutritional fiber. Avoid refined sugar & junk carbohydrates. Avoid alcohol, sweetened juices, soda & caffeinated beverages. Aim for 7.5 to 8 hrs of sleep / night. Hydrate w at least 64 oz of water / day. Calories burned must > calories consumed. Do both cardio & weight >

Rather large amount.: It is reasonable but difficult to lose 1 lb / wk, less reasonable and quite difficult to lose 2 lb / wk. Running burns 600 Cal/hr and there are 3600 cal in a lb of fat. Losing 1 lb per week would require 6 hours of running without increasing intake or some smaller amount along with reduced intake. Play with the math and see what combo works best for you.