Forget my secret answer :(

It's happened to me too at some point, maybe I should stop making up pet's names because I'm too lazy to think of a real secret question ..oO

If you really need to know, try our Billing Department:
http://www.wow-europe.com/en/support/accountbilling.html

I don't recall whether they can retrieve it for you, or whether they can reset it. I do assume, however, that you'll need proof of identity and account ownership, etc.; so have that stuff ready if you call them.

I also have to add, for all those people who say they never got an answer or have been waiting for months:
I would say that 20% of the people I email from work have Blizzard emails automatically go to their spam folders. Must be something in the water..