If the judgment was obtained through summary judgment, as you say, then you would have had to have filed an answer at some point. Since you deny being served, I'm guess that the judgment was obtained by default. In other words, the plaintiff told the court that he served you and that you never answered the complaint.
You can file a motion, under certain circumstances, to set aside the judgment. If the case is in justice court or small claims court, just go to the court, ask for a form and file your motion. If the case is in Superior Court, I'd suggest finding a lawyer to help you.
A summary judgment will only enter after a suit has been filed and served and the defendant has answered the complaint. It sounds as if a default judgment may have been entered against you. I recommend you go to the courthouse and look up the case and contact an attorney to assist you
You can move to set aside a judment if it was entered by mistake and sometimes if you have a valid defense but did not know of the action against you. Look at Aarizona Rules of Civil Procedure rule 60 (c) and the cases discussing the rules. One of the requirements is that you act promptly so do not wait,