passwordresetdisk

What version of windows, Which password. In Winnt, Win2k, and Winxp there is an administrator account, if you use that you can change passwords for local users. If you need the administartor account password changed, you should go to wininternals.com and get ntfsdos or erd commander.
If the accounts are domain accounts the passwords should be able to be reset by the server administrator or server team.

Some of the older motherboards have reset jumpers on the board. If all else fails and you don't want to have to reformat, take out the CMOS battery for 15 minutes. Any BIOS settings you have adjusted will be lost. BIOS will be reset to factory defaults.