The court must have personal jurisdiction over you to enter an order. You may be able to contest the court's jurisdiction based on improper or non-service of the initial action. You will need to take all of your information and copies of the documents to an attorney so they can evaluate whether you have sufficient proof to show you were not served. I often have people tell me they were not served (given notice of the action) but there is an affidavit in the court file from the process server...