I'm not saying this to be mean or rude, but just IMO, if you don't want something possibly stolen, make SURE you get it copyrighted in your name before you put it publicly on the internet. I myself have a copyrighted poem on redbubble.com . Take a look at their website when you get a chance. It's something you may be interested in. But even there, like, I have many poetry that I've posted publicly. They were good to say the least, but now I can't use them in my upcoming book that I'm working with my brother and a friend named John. I mean, I could use them, but since I didn't copyright it right. This is just my opinion. My intentions are for the good. If it was already copyrighted, then, again, my opinion is to find out who it was and then contact whomever you can like authorities.
I'm sorry to hear it was stolen though.