How is a flat nose corrected?

There are many ways to do this ranging from non surgical with filler through to surgical augmentation with Medpor or rib/caer cartilage

That is too open a question. It's like asking how do you get from New York to Los Angeles. There are a lot of ways and the space is too limited in this format to do a full description. Textbook chapters are written on the subject.I hope you realize that this format of posting questions and receiving answers lacks the face to face direct communication required for you to make an informed decision regarding surgery.My response to your question/post does not represent formal medical advice or constitute a doctor patient relationship. You need to consult with i.e. personally see a board certified plastic surgeon in order to receive a formal evaluation and develop a doctor patient relationship in order to know if this assessment is valid.

Many ways to fix the flat nose. I need to see photos to give a proper answer. In general the nose needs grafting of cartilage from your septum and possible narrowing your nasal bones. See a very experienced rhinoplasty surgeon who does natural noses.