You need to bring a motion to vacate the judgment for lack of notice in the court that entered the judgment. An attorney can do this for you if you are out of state. Then, if you really owe the money, you will have leverage to negotiate a settlement, and if you do not, then you can fight the case.
Michael D. Siegel, Esq.
Siegel & Siegel, P.C.
One Penn Plaza
New York, New York 10119
Serving the metro New York area, including New Jersey