You need to make an appeal. Here’s how:
Step One: Click “New Topic” in the upper right hand corner of your screen.
Step Two: Fill in the title (I would call it phonggdk’s ban appeal) and then click “category”.
Step Three: Click “Terraria Server Ban Appeals” category. Follow the instructions it gives you on the template, and fill it out to the best of your ability.
Hope this helps, let me know if you are having trouble with the process.