Can someone help me on the public server, my iron door was stolen, diamonds were stolen, almost everything but my wood, cobblestone, and my dirt.

did you put signs over your chests that say [Private]  ?

No, i only put it on one but i'm pretty sure i needed 2 for a double chest.

If it was just chests looted I'm afraid we can not do much as blocklogs do not show who opened and closed chests, unless there were any blocks broken there's nothing we can do. We apologize for the inconvenience.

50 already helped me, he even stole my door.

 You only need one sign for a double chest.

 No, you need two.
You also have to put [Private] on the top line on both.