Hi I Am Wanting Some Medical Advice. @ Years Ago

Hi I am wanting some medical advice. @ years ago I had mouth surgery and lost alot of weight. I was in a 40 d cup bra but i lost weight in my breasts. When I lay down its like they disappear and I dont have any. I weat a C bra now but i want to gain my weight back in my breasts. I didnt have this probelm until I had the surgery. Is there a way I can gain my breasts back?