If i want to bulk up in body size which food is necessary because as far as i can tell nothing is working for me..no matter what i eat i always thin?

Slow down: People under extrem stress may have hard time gaining weight. Avoid extreme hot weather, protein shakes, eat calorie dense food and do weigh lifting

Sounds like you need: To take stock of how many calories you are consistently consuming and how many you are burning. You need to be consuming more than your are burning to gain weight. First you may want to see your doc to make sure there isn't a malabsorption or hormonal reason for your weight gain issues. Otherwise, you will need to focus on consuming calorically dense foods like nuts, beans, avocados, oily fish.