Judgment by default was entered because an answer to the complaint was not timely filed with the court. You should file with the court a motion to set aside the default. It should be filed with the court with an attached proof of service and served by mail on the opposing party.  Your argument supporting your motion to set aside the default is that you never received notice because you were never served with the summons and complaint and therefore could not have timely filed an answer to the complaint.If the judge grants your motion to set aside the default, the case will then be back on track and litigation will continue.