Yes it is possible by healthy diet chart
. Weight gain is a gradual process. You have to keep patience and 3-4 kgs weight gain is a safe weight gain which includes muscle mass not fat. So first of all you start taking small frequent meals. Eat at right time. Increase your fluid intake. These are the general tips but everyone has different body type so same advice can't be given to others and for customised diet
chart a clinical dietician needs to take medical history, diet recall, your activity level schedule as well and then can plan specified diet chart for you.