#2 - Aug. 1, 2010, 6:41 a.m.
It doesn't look like the account itself was compromised, Daniek, do you have a sibling or "friend" that may have gained access to the account and deleted the characters?
It looks like the characters were just deleted and nothing else happened, that usually happens when someone you know gains access to the account or you decide to delete your characters and then change your mind.
The reason for it doesn't really matter except if someone did gain access to your account you'll want to check your password and make sure they are unable to log in again.
You'll want to submit an in-game petition and request that these characters be restored. It doesn't appear that you have done this yet. The sooner you can do that the faster your request can be looked into. Though no restoration is ever guaranteed it is very likely that we'll be able to help. :)
Good luck.