If you MEAN a hard-disk password, then you are in serious trouble.
Hard-disk passwords are normally set in the BIOS configuration screen
(although some OEMs provide a Windows applet to do so, and characteristically
don't tell the user just how important it is to never, ever get this wrong!)
A hard-disk password cannot be overcome. To recover use of the disk it must
be 'reset' with a utility from the disk manufacturer. This will destroy all
data on the disk, leaving you with the need to reinstall Windows, programs,
and data from scratch. It's designed like this because the whole point of the
HD password is to prevent your data being read, even if the disk is stolen.
Note; before acting on above, check that it IS a HD password that's involved
and not a BIOS or Windows password, whose loss is less serious.
