most likely someone got your account password...they log in take all your gold equipment etc then delete your characters. If you "might" know who has access to your account take it up with them. If you have no clue who it could have been then you need to run an antivirus and spyware detector on your pc as you probably have a keylogger installed somewhere.
So get your PC checked out as soon as possible....then change your account password ASAP and never hint/tell/reveal anything about your password to anyone.
You have this thread in Riverside as well. If Anet has already stated there's nothing they can do, then there's nothing to be done. Surely, if ALL that happened was your computer crashed and you relogged immediately to find everything gone, it would have been a server glitch of huge proportions and they would have looked into the problem.