Underweight. Pls suggest me diet plan!

Iam underweight my weight is about only 32 if I drink any protien powder I will gain weight of not I won't gain weight day by day my weight is decreasing I have heridatory issue to underweight after getting marriage is there any problem for me and my fingers and leg fingers are very small and I can't wear ring too if I wear means it collapse how to overcome this I don't know I need to gain weight but my body won't able to gain the necessary weight it's too hard for me feeling depressed for not gaining weight iam losing everything pls give me necessary food chart and tell me how to gain weight in home and naturally I need to gain weight if I drink milk with honey means it becomes constipation if I drink Horlicks also I feel the same and I can't eat too much I feel constipation how to overcome this problem I too don't know I don't have interest in anything pls suggest me diet plan