I honestly think the best thing you can do is really have a good sit down and start typing down in notepad password possibilities.  Are you the type of person to replace e's with 3's?  Are you the type of person that uses the same password over and over, but just changes it slightly?

Try to recreate your surroundings at the time when you would have created the password.  Down to re-arranging the room, perhaps even re-creating the day that you did it (if you do remember anything at all about it).  Memories work in funny ways, and sometimes just re-living an experience of that day can spark the retrieval of a memory of what you did.

I wish you all the luck in the world.