Not sure if it will work on your drive, but you can try the VSC security erase, that on some WD drives can success erase it and remove the password. (if I remember good...)

1. Download the tool "atapwd.zip" (written by Alex Mina)
2. Create a bootable DOS disk, and put atapwd.exe on it
3. Boot it and run atapwd.exe
4. Select the locked harddrive and press enter for the menu
5. For Fujitsu disks: Choose "unlock with user password", then "disable with user password". The password is empty, so just press enter at the prompt.
6. For Toshiba and Hitachi disks, if the above doesn't work: Choose "unlock with master password", then "disable with master password". The password is all spaces.
7. For WD, The password id "WDCWDCWDCWDCWDCWDCWDCWDCWDCWDCW"
8. Your disk is now unlocked. Shut down the computer and remove the disk.

Still locked?
-------------
If the above suggestions don't work, here's some background info about the disk lock feature:

The disk lock is a built-in security feature in the disk. It is part of the ATA specification, and thus not specific to any brand or device.

A disk always has two passwords: A User password and a Master password. Most disks support a Master assword Revision Code, which can tell you if the Master password has been changed, or it it still the factory default. The revision code is word 92 in the IDENTIFY response. A value of 0xFFFE means the Master password is unchanged.

A disk can be locked in two modes: High security mode or Maximum security mode. Bit 8 in word 128 of the IDENTIFY response tell you which mode your disk is in: 0 = High, 1 = Maximum.

In High security mode, you can unlock the disk with either the user or master password, using the "SECURITY UNLOCK DEVICE" ATA command. There is an attempt limit, normally set to 5, after which you must power cycle or hard-reset the disk before you can attempt again.

In Maximum security mode, you cannot unlock the disk! The only way to get the disk back to a usable state is to issue the SECURITY ERASE PREPARE command, immediately followed by SECURITY ERASE UNIT. The SECURITY ERASE UNIT command requires the Master password and will completely erase all data on the disk.

Try ZU:...
I don't know if your model is supported.

Sorry, usually we say "VSC secure erase".

There you have a good resume https://www.rockbox.org/lock.html
The exact master passwords are written somewhere at hddoracle.
For Hitachi, the master password is many spaces (I do not recall how much)
Newer drive may have newer unknown password...
There is also the "zu" tool that can maybe help you.

I repost the main infos from the rockbox.org page:

Quote:

1. Download the tool "atapwd.zip" (written by Alex Mina)
2. Create a bootable DOS disk, and put atapwd.exe on it
3. Boot it and run atapwd.exe
4. Select the locked harddrive and press enter for the menu
5. For Fujitsu disks: Choose "unlock with user password", then "disable with user password". The password is empty, so just press enter at the prompt.
6. For Toshiba and Hitachi disks, if the above doesn't work: Choose "unlock with master password", then "disable with master password". The password is all spaces.
7. For WD, The password id "WDCWDCWDCWDCWDCWDCWDCWDCWDCWDCW"
8. Your disk is now unlocked. Shut down the computer and remove the disk.

Still locked?
-------------
If the above suggestions don't work, here's some background info about the disk lock feature:

The disk lock is a built-in security feature in the disk. It is part of the ATA specification, and thus not specific to any brand or device.

A disk always has two passwords: A User password and a Master password. Most disks support a Master assword Revision Code, which can tell you if the Master password has been changed, or it it still the factory default. The revision code is word 92 in the IDENTIFY response. A value of 0xFFFE means the Master password is unchanged.

A disk can be locked in two modes: High security mode or Maximum security mode. Bit 8 in word 128 of the IDENTIFY response tell you which mode your disk is in: 0 = High, 1 = Maximum.

In High security mode, you can unlock the disk with either the user or master password, using the "SECURITY UNLOCK DEVICE" ATA command. There is an attempt limit, normally set to 5, after which you must power cycle or hard-reset the disk before you can attempt again.

In Maximum security mode, you cannot unlock the disk! The only way to get the disk back to a usable state is to issue the SECURITY ERASE PREPARE command, immediately followed by SECURITY ERASE UNIT. The SECURITY ERASE UNIT command requires the Master password and will completely erase all data on the disk.

I suggest you firstly looking in what mode (High/Max) is locked your drive, and if master pass is modified or not, with this hdparm command:
hdparm -I /dev/hdb

What is the number of "Master password revision code = ?????" from the hdparm output, post the output.