It's not 100% clear exactly what the OP is asking about, but a hard drive password is not the same as a BIOS password. a hard drive password is to stop anyone accessing data on the hard drive even if it was removed from the computer all together, this type of password can even stop the drive being formatted in another computer as the lock is built onto the controller on the drive.
Generally if you set a hard drive password and forget it you're stuffed.
But as ever, all computers are different and with only snippets of information to go on it a bit hard to provide reliable answers.