Possible Duplicate:
Windows 7 administrator password lost! How can I log into Windows 7 without a password?
I reset my password (windows 7) a week ago and now have totally forgotten the password. How do i reset the password?
Possible Duplicate:
Windows 7 administrator password lost! How can I log into Windows 7 without a password?
I reset my password (windows 7) a week ago and now have totally forgotten the password. How do i reset the password?
Assuming you don't have whole-hard drive encryption (such as BitLocker), you can use Petter Nordahl-Hagen's Windows NT/2000/XP/Vista/7 offline password editor.
If it's an simple password (such as a word you'd find in a dictionary), the Ophcrack live cd can break it in a matter of seconds.
Get the Vista edition, as Windows 7 uses the same login system as Vista.
Kon-Boot live cd in its current compilation state it allows to log into a linux system as 'root' user without typing the correct password or to elevate privileges from current user to root. For Windows systems it allows to enter any password protected profile without any knowledge of the password.