Well, if you want to reset your password (from another user account with admin privileges) then here's what you do:
Go to Start>Run and type mmc
Go to File, click Add/Remove Snap-In...
Click Add then select Local Users and Groups
When the "Choose target machine" window pops up, just leave it at Local Computer and click Finish.
Close the list of Snap-In's and click OK on the remaining window.
Now, expand the branch under Local Users and Groups
Click Users and find your account on the box to the right.
Right-click the account of which you want to change the password of, and click Set Password...
Set your password and you're good to go!
This method is kind of a last-resort password-reset technique, and should only be used when you have no other choice and nothing else works.