8 Answers

Phone a cousin ... cousins always seem to know the little details.

I have two cousins that remember everything about my family.  I have found this to be very useful at times.

Look on your Birth Certificate or Adoption Papers.

How old are you? How in the world can a person forget their mother's maiden name? Start with Smith and work from there.................

shame on you! ask her if she's alive...

Good idea to check with a family member who would know.  But, didn't you have some security questions to answer that could help you recover a lost/forgotten password?  
Name of your first pet?   Bet friend?    OH! Your Mom's maiden name IS your security question.
Bummer. 

Don't you know any of her relatives that have the same last name as hers ?

You are a very unique person! I don't think I've ever heard of anyone doing that before!

Ask her what it is! simple, we are after all only human and all humans err