You might be able to rescue your computer by enabling the normally hidden / disabled Administrator account and use that to possibly fix the password problem on your local user account.
You'll need to boot from the installation media. If you do not have the installation media on hand you can download the ISO from here
Once you have the ISO, you can use ImgBurn to burn it to a DVD, http://imgburn.com/
or Rufus to burn it to a USB ThumbDrive, http://rufus.akeo.ie/
either of which you can use to boot your computer.
Follow the steps outlined here