Locked Hard drive

I have a hard drive that seems to be locked. Once it boots up to win 2000 it asks me for the password (ctrl + alt + del) since i don’t have it how can i access this HD and change it or if i try to install a new operating system on it and set it up to boot from cd-rom,it wont do it. How can i go around this password issue or be able to boot from cd when HD seems locked?