Hard drives on laptops come with the ability to make an access password on the hard drive itself in the controller. It is an added security feature for mobile computing.
It is also a pain in the arse. If you lose the password, or don't know the password. It is basically impossible to crack. Depending on the model there are programs and backdoor master passwords that might allow you to access the drive. There are also techniques you can use, albeit advanced. I have a friend that got a bunch of hard drives in bulk from the government. They work in every way except, you cannot access them to format because of the password based in the controller.
You can mirror the drive with an identical drive to fool the secured drive to change password but it is advanced techniques involved and may not work.
Generally when one forgets the drive password. You have to return it to the manufacturer or use an independent company to crack the drive.
You are better off to replace the drive as you will spend just as much paying an outside service to access the drive.
Sometimes if you can prove you own the laptop drive, you can get your laptop and/or drive manufacturer to resolve the password.