What should I do if my mobile phone password and username suddenly become useless?

Modify/clear the password of the administrator account "User Account" in the WinXP control panel allows you to modify the password of the user account, but not the password of the administrator account. If you want to change the administrator's password to abc 123, you can do this: enter MS-DOS mode and enter the command net user administrator ABC 123 to enter. To clear the administrator account password, you can go to the disk where XP system is located and delete the SAM file in the system installation directory (Windows\system32\config); After restarting the computer, the administrator account has no password. If you log in to the system with an administrator account at this time, you can enter the system without entering any password.