You are kind of stuck here. There is no file that contains the passwords in Windows 2000. Here is what Microsoft says about passwords in Windows 2000. You may end up reinstalling the OS on this PC or worse, reformatting and starting over. Anyway, this info from Microsoft will shed some light on this for you.
If a user password is lost, forgotten, or unknown, the only method to reset the
password is for the administrator (or a user with administrative access) to log
on and reset the password in Computer Management. There is no method in the
Windows 2000 security model to bypass, disable, or reset the password.
If the administrator password is lost, forgotten, or unknown, access to the
computer may not be obtainable and the operating system may need to be
reinstalled.
The Windows 2000 security framework is designed to fulfill the most stringent
security requirements.
The Windows 2000 Setup program creates a user account called Administrator on
your computer that has administrative privileges for managing the overall
configuration of your computer. The Administrator account is intended for the
person who manages this computer. For security reasons, specify a password for
the Administrator account. Leaving the Administrator password blank indicates no
password for the account.