Do you know locking/unlocking capability of your hard disk? If not, read following.
Every hard disk has inbuilt controller, called ATA controller. ATA stands for Advanced Technology Attachment or AT Attachement. ATA is the standard protocol to interact with the hard disk. ATA protocol has several commands using which hard disk can be locked or unlocked.
This lock is the hardware lock. Once hard disk is locked, you can't read/write from your hard disk, until unlocked. Once it is locked, all commands to hard disk will be aborted, except commands for unlocking and some special commands.
Almost all modern hard disk support security feature. By default security feature is disabled. It needs to be enabled and then only hard disk can be locked/unlocked. Some older hard disk might not support this feature.
My older hard disk doesn't support security feature. To test this utility, I bought new one which supports security feature and I was able to lock/unlock it.I had installed OS on my older hard disk. Then plugged in both of the hard disks. Newer one I had locked using this utility. When windows boots up, it only able to recognize my older disk, not the newer one. I was not able to see any drives pertaining to my newer disk, in the explorer. Then I booted the PC in DOS mode, run the utility, unlock the newer one disk and reboot again. Now, OS has detected both the disks and able to see drives of newer disk in the windows 'explorer'. It is very easy, if you know password you have used during locking. But if you forget the password, forget your hard disk also!!!