In last chance, u can buy a new cd key and ask for an account transfer. Dupre can do this
If u buy a new key, take it on steam this time, you can't lost it there.
Also, try to take a look in your regedit, maybe you can find a trace of your key on it (not realy sure for this), use what I wrote in previous post and see if the "serial_key" is present. If yes, just copy the key value somewhere.