How could an USB work to reset Windows 7 password?

To reset Windows 7 password, we often need a password reset disk which can be a CD/DVD or USB flash drive. How to create that disk with USB?
Tip 1. Create Password Reset Disk by Windows

1. Insert a USB flash drive into the computer.
2. Click 'Start' button to select 'Control Panel'.
3. Click 'User Accounts and Family Safety'.
4. Click 'User Accounts' when a new screen appears.
5. Click 'Create a password reset disk' in the leftpane.
6. Follow the instructions of Forgotten Password Wizard.

After creating the disk, you'll find a 'Userkey.PSW' file when you open the USB flash drive. Keep the USB flash drive in a safe place. You'd better to mark the USB flash drive so that you can distinguish it from other USB flash drives.

Tip 2. Create Password Reset Disk by Windows Password Recovery Tools

Although windows provides the way to reset forgotten password, many users forgot to do that or even do not know that way, so windows password recovery programs are developed, such as ophcrack, Offline NT Password & Registry Editor and Windows Password Buster. The former two are free ones, but having complicated operations. Here we take Windows Password Buster for instance.

1. Burn a password reset CD/DVD or USB.
2. Boot locked computer from the burned disk.
3. Reset forgotten Windows 7 password.

The password has been successfully reset and now you can log on your computer without password.