The standard unlock process involves in using the master password or serial number in case you have forgotten the master password. If you don't have access to these options anymore, I recommend using a trick to delete a file used by Folder Lock.
We need to locate the file first. To do this, go to Start > Control Panel > Appearance > Folder Options, click the View tab, check the Show hidden files, folders and then OK.
You will need to find
win_mpwd_sys.dat. The file is known to be located in the following directories:
C:\Windows\SysWOW64 or C:\Windows\System32 (for a x86 computer)
Delete the file, reboot the PC and the protection should be removed allowing you to access the contents of the "locked" drive.