It's a rare situation, but it happens. And when it happens, simply sacrificing the locked-out user account may not be an acceptable option.
TechRepublic has an excellent overview of the Offline NT Password & Registry Editor, including an illustrated guide to using the tool on a typical locked-out Windows system. (A video tutorial is also available here.) Here is how the TechRepublic guide describes the tool and its basic functionality:
"Offline NT Password & Registry Editor is a free Linux-based utility, which as the name suggests, works offline. The code creates its own boot environment. Once you burn the ISO image to a CD-ROM, youï¿¼ll have a tool at your disposal for resetting Windows NT, 2000, XP and Vista account passwords. You wont even have to know any of the current account user names or passwords on the system to make it work.
Instead, the utility detects user accounts and enables resetting the password to a value you decide. The application will even reset locked or disabled user accounts."
Instead, the utility detects user accounts and enables resetting the password to a value you decide. The application will even reset locked or disabled user accounts."The guide includes several prominent caveats, all of which are appropriate given the inherent risk involved in using a tool like this one. Perhaps the most important of these is a reminder that resetting the password on a Windows account using the Encrypting File System will almost certainly render the encrypted data permanently inaccessible.
If you're stuck with a true emergency and accept the risks, the Offline NT Password & Registry Editor just might save you an immense amount of time, trouble, and money. It might even save your job, if you're the one who gets held responsible for a password that goes missing.
You can get the tool itself from the developer's site here; alternately, it is also available as a download from Extreme Overclocking (a legitimate site that provides tools and resources of interest to PC system-building enthusiasts.)