Elcomsoft forensic disk decryptor software can sometimes be used to decrypt a drive that is utilizing whole disk encryption.
Elcomsoft
Forensic Disk Decryptor is
a software that Perform the complete forensic analysis of encrypted disks and
volumes protected. It has two access modes: Full Decryption and Real-Time
Access to Encrypted Information. There are at least three different methods for
acquiring the decryption keys. Its license price is $299.