Hacking a Windows password you can try a free recovery tool, Offline NT Password Editor, to remove the password. This way requires you to download the Live CD and burn the ISO image to a CD. Then boot your computer from it, so you can remove any user account password of your Windows system after it starting.
Details instruction:
http://www.asunsoft.com/blog/how-to-removeclearerase-windows-7-password-with-offline-nt-password-registry-editor/

I have tested another method to hack a Windows password and get success. Compare to this: How to Hack Windows 7 Password.