How do I regain access to a Truecrypt volume?

Okay, I changed the password on my truecrypt volume a couple of weeks ago. Stupid me forgot to backup the header file, and I’ve forgotten the password. I know it’s not a terribly secure password (I think I know the first 5 characters, just not the last ⅔) but no matter what I do, I can’t seem to regain access to the volume.

Is there a way to have a program automatically guess the password based on what I do remember from it?

EDIT: I use Windows 7 if that makes a difference.