Hi,
Sure will help you, but more details are required to recommend anything. Weight gaining is a gradual process, it will take time and keep patience. You should follow a balanced nutritious diet which contains good quality and quantity protein, like egg, chicken, milk, dahi/ yoghurt, paneer, soyabean, almond, cashew, sprouts etc and along with fresh fruits and vegetables. Drink 3 litre water per day and do some exercises which will helpful to increase your metabolic rate, thus food intake will be more.
Next Steps
To get personalized diet chart you can consult with me on practo.
Health Tips
You can have calorie rich food, like khichdi with moong-masoor, fruit custard with nuts, vegetables stuffed omelette etc, which will help to gain weight.