I don't know anything about playing as a guest.
Was your old account named Shoot_The_Target or EnderSir6? You seem to say both. Do you mean that your account was EnderSir6, and it contained a knight named Shoot-The-Target? (Notice the hyphens, not underscores.)
Was this account through www.spiralknights.com, or Steam, or Kongregate, or Armor Games, or what?
While you answer these questions, and wait for responders with more knowledge, you might try contacting tech support. But I'm not sure what they can do, if you're not totally sure about your account name.