If you are locked out of a computer, you must reset the password to regain access. In the latest versions of Windows and Mac operating systems, the system stores the password in an online account, and you can reset the password on another device. If multiple users have administrative access on either operating system, you can log in as another user and reset the password.
Password resetting is available in the Control Panel under User Accounts in Windows. Microsoft allows users to create a password reset disk, but you must do so before you are locked out. Advanced users can modify the registry by using an installation disk, entering Repair mode and overwriting the code, but they may permanently lose access to encrypted files already on the machine. Third-party programs, such as Ophcrack and UNetbootin, can recover the original administrator password and restore access to encrypted files.
On Mac operating systems, reset the password under Users and Groups in the System Preferences window with another administrator login. You can also request a password hint by clicking on the question mark icon on the log-in screen. If you have a Recovery Key with FileVault, you can use this to reset your password. Otherwise, the system automatically launches the Password Recovery Assistant if you reboot your system and do not enter any password for a set period of time.