On a list of unpleasant things occurring to players in any MMO, “getting your character deleted while you’re still playing” is probably near the top of that list. It was also something that started happening in AdventureQuest 3D, much to the surprise of the game’s development team. The good news is that the problem has been fixed, the better news is that the characters were not permanently deleted and can be restored, and the best news for people who love hearing details about these things is that you can learn all of the details in a full-on story about what happened and why.
The short version is that someone found a way to essentially “trick” the servers into accepting that a DDoS attacker was logging in with the account of other players, followed by triggering the character deletion (which actually just sends the characters in question to a queue for permanent deletion, hence ensuring that you can have your character restored). It’s far more detail than you usually get in stories about these sorts of hacking, so if you love a good detective story about account breaches, you’ll have fun with this one.