OS X WoW password troubles

I have recently downgraded from ML to SL.
I want to reinstall wow but have no idea about my password, nor my security question (haven't played Wow in over 6 months).

Am I in trouble ?

Got it back !

Right, that's solved.
Now, have reinstalled WC3. Haven't been playing for a very very long time so my login and password no longer work.
Only my battle.net login I use for WoW is not useable for WC3 (login has a limit of 15 characters and mine is a lot longer than that). So now what ?