You have gained physical access to a Windows 2008 R2 server which has an accessible disc drive. When you attempt to boot the server and log in, you are unable to guess the password. In your toolkit…

John the Ripper is a password-cracking tool that attempts to recover passwords via brute force or dictionary attacks, not directly modify or bypass them in the SAM database.

SET (Social Engineering Toolkit) is used to craft phishing and social engineering attacks, not to manipulate local Windows account credentials.

CHNTPW (Change NT Password) is a specialized Linux tool that mounts a Windows NTFS partition and edits the SAM registry hive directly, allowing an attacker to blank or change any local user password or re-enable disabled accounts. It requires only physical access and bootable Linux media, making it ideal in this scenario. No knowledge of the existing password is required because it overwrites the hash directly.

Cain and Abel is a Windows-based credential recovery and sniffing tool and cannot be run from a Linux LiveCD environment.