I'm going to be completely honest, I had a good chuckle reading the question.
Allow me to explain myself; Do you really think such a big deal would be made out of port forwarding (you know, all of the topics that accumulate in Help every week, the topic at the top of this board, the message box that appears when you click "Internet" on the Start a Game menu) if it didn't do anything at all?
Before you go breaking your possibly correctly forwarded ports, you need to make sure your server is really dead. Maybe people just aren't coming to your server. It happens; people don't find your server name interesting or intelligible (you know, maybe they don't want to join a deathmatch server or a AWSOME FAMLY RP FREE ADMIN NEED PUPPY server), or maybe nobody is looking for a server to join. You can start a dedicated server (which to do so, run dedicated.bat in your Blockland folder) and try to join it from the Query Internet section of the server list. You can always ask someone on the IRC to check for you if you want. If it's dead, then you've got a problem.
In this case, make sure you did EVERYTHING in the tutorial. This includes that TCP bit, and making sure your firewalls are letting Blockland through.
