Hmmm.....you definitely need to check your state laws to see if you were served properly. If you were not served properly, you may be able to file a motion to vacate the judgment.
Check here and see if you can find out....
Ohio Rules of Civil Procedure, Process Serving Laws ? ServeNow.com
You can call the courthouse and have them look up the case. First make sure there is actually a judgment against you (they can verify this) and then also ask them how/if it is noted as to how you were served. They are supposed to have proof of service included in paperwork they receive.