I want to gain my weight.is whey protein is helpful for weight gain?

It is used by some: For this purpose - especially when combined with weight lifting. Eat healthy high calorie foods. Eat 6 meals/day. Work on strength training to build your large muscle groups. Workout w heavier weights w fewer repetitions. Sleep at least 8 to 9 hrs/night. Hydrate well w water. Foods to help w healthy weight gain: almonds, cashews, pecans, sunflower seeds, flax seeds, walnuts, hummus ; avocados.

Protein helps but: You should gain weight, but do so responsibly. Meaning that protein alone won't help unless you supplement properly with carbohydrates, the good fats, and practice a diet that is healthy. Supplements help, drink plenty of water and exercise. I would consider a personal trainer or nutritionist. Make sure you ok diet with a dr.