potential soloution

          1.          Boot your Mac and hold down ⌘-R (Command –R) to boot from the Recovery HD partition.

          2.          Open Disk Utility.

          3.          Select your locked hard drive.

          4.          Under the File menu, select Unlock “Drive Name”

          5.          When prompted for a password, enter the password of the authorized account on the drive.

          6.          Once you unlock the disk, hold down the Option key on your keyboard and click on the File menu.

          7.          Under the File menu, select Turn Off Encryption… with the Option key held down, it is no longer grayed-out.

          8.          When prompted for a password, enter the password of the authorized account on the drive.

          9.          Disk Utility should display a progress window labeled Starting conversion to JHFS+

          10.          Your drive should now be unlocked.