My bmi is no correct. i am highly underweight. now i am 22 and my weight is around 52 kgs. so kindly suggest me some tips for increasing my weight.?

How do you feel: Not knowing your height , it is hard to advise you. But if you are feeling tired and run down, it may be nutritional. If you have lost weight with out trying you may have a medical condition which is hidden. Start learning about how many calories are in your food. See your doc if things aren't adding up.

Start with med eval.: Eat healthy foods high in calories. Eat 6 meals /day. Work on strength training to build large muscle groups. Work out w heavier weights w fewer repetitions. Sleep at least 8- 9 hrs/night. Hydrate well w water. Foods to help w weight gain: almonds, cashews, pecans, sunflower seeds, flax seeds, walnuts, hummus, avocados, granola, trail mix, dried fruits, protein shakes & bars, lean meats & poultry.