I was suing my landlord and never received documents notifying me of my court date. Then I received a notice saying that since I didn't show for my court date the judge ruled in the deffendants favor and now I have to pay the deffendant for counter suing.

So you go back to Court, ask that the Judgment be set aside because you weren't served. The Court will have whatever proof of service is on file. That's what you will dispute.

Yes, go back using the improper service. BUT, unless it is close to the time limit on filing, they may also merely refile normally. So do you have good evidence or proof that you don't owe the money ?