It is unclear what you mean by "we did not respond." Proper service is required, but proper service may have actually been made. Your sons may not be giving you all of the facts. When one is properly served and does not attend court, a "default judgment" can occur, with the consequences you are listing. The son against whom the judgment was made needs to talk to a lawyer. The lawyer needs to determine whether or not the state can prove that proper service was made and can then try to minimize the damage. Good luck.