Summary: Harry Potter from fifth year on was trained in every kind of magic imaginable from the aurors to the unspeakables and the spell creators. By the end of his would be seventh year he had learned almost everything there was to learn about magic, including becoming quite brilliant in wandless magic, and was ready to face Voldemort. In the end he defeated Him, but by the time it was over he learned exactly what it was that he lost.
After spending years pretty much isolated except for his teachers he didn't realize how much had happened while he had been gone. He had been kept uninformed so he could stay focused on his training. After everything was over he learned of what he had missed, he had lost everyone . . . Ron, Hermione, the rest of the Weasleys except for Bill and Charlie who were back in Egypt and Romania respectively, Remus, Sirius, Neville, and countless others.
After hearing about everyone Harry disappeared to start a new life in the muggle world. He moved to the US and got caught up in his non-magic subjects and headed to university wear he is got his Doctorate in Forensic Anthropology and has just been signed on as Dr. Temperance Brennan's new assistant. He is now 25 years old.
Side Note: Harry Potter decided to go into forensic anthropology after learning that while the bodies of his friends had been found many could not be indentified, meaning that they couldn't tell one victim from another. While magic could do many things it couldn't do that thereby influencing Harry's decision for getting a degree in forensic anthropology. He has also kept in shape through daily workouts and martial arts. He is also licensed to carry a gun. It is so he can protect himself without resorting to magic.