Hi @Deepa & @nisha i think its a very common problem, given our sedentary lifestyle and food habits. I think if we try to live a healthier life , workout daily and eat healthy, It shud help drastically. I have a frnd who had gynecomastia when we were young. But he went on strict diet and rigorous workouts everyday, and within 4 to 6 months he lost a lot of weight and along with the weight , even the chest became flat.
But even after this if its not helping u, I recommend u Consult a endocrinologist in ur city.