You will need a lawyer with experience in educational/administrative hearings.
While you say you have "provided enough evidence", it seems the school thinks otherwise, or it has withdrawn your money in error. You should first contact the department in charge.
It is indeed possible to sue them, but your best chance in this matter would be to have an attorney contact them and have the school change your status to in-state based upon the evidence provided.
Hopefully this will help you.
Felipe B. Fulgencio, Esq.
Fulgencio Law | Hyde Park, Tampa, Florida