ATA (BIOS) Harddrive Password Lock - BYPASS

The BIOS/CMOS (Basic Input/Output System) is a very necessary peace of hardware in your computer. It manages where power should be used and what hardware is available as well as many other jobs.
1-1 (BIOS)

It has access to all of the hardware and can set limits of access and different boot devices.
What i will be talking about is the Specific setting in the BIOS called the HDD ATA lock.
Here is a example of the setup process of the HDD lockup. You can see that the window is prompting the user to set a password. Once this is done the HDD will be locked on boot until someone puts in the password.
1-2 (BIOS Settings Screen) Normally Acquired by pressing f10 or f2 depending on the PC

Most people use this for obvious reason, security. But there is a major flaw is this type of security, if you have physical access to the computer, putting in a different hard drive of the same type that is not configured in the BIOS settings to lock, the BIOS will not prompt for a password. In a regular sanario you would see this
1-3

Or something like the image above. Once the non configured HDD is installed the BIOS should boot up regularly. Then Go into the BIOS again, then reinstall the old locked HDD and goto the password settings like the picture above (1-2) and set the password to "Enter" again (Just press enter and make it blank).
If this doesn't work and the lock is still in affect, like a boot up lock. Then disconnect the PC or laptop, Remove any battery if any are present, and go in and search for a round battery that should be on the motherboard normally around the southbridge chip set. You'll be looking for something like this:

Remove it and let it sit for 10 min. Press the power botton for 1 min (To drain any power) before replacing the BIOS battery. Plug everything in and restart the PC and the BIOS settings should of reset. I've had success with laptops before by using these techniques. I wish the best of luck.