I am very slim i want to gain weight through vegetarian diet. how to gain muscles and some fat over body in controllable manner ?

High protein diet: Your body needs protein to build muscle and strength. Weight baring excercise helps to stimulate muscle production. L carnitne may also help.

Use BMI: Use a bmi calculator. Many in the market/internet. Bmi between 19-25 it's normal. Below 18 it's not healthy for you. I see you are dealing with emotional problems. Be very careful with your weight. Do not get fixated with being slim. Look at your inner beauty. You are loved. God, friends, family. But, you have to love yourself first. I will pray for you. Sachisaini43.