With BitLocker Drive Encryption, you can help protect all files stored on a drive (operating system drive) and a fixed data drive (such as an internal hard drive) that has Windows installed. Files remain encrypted only if they are stored in an encrypted drive. Files copied to another drive or computer will be decrypted. If you share files with other users, such as through a network, the files remain encrypted when they are stored on the encrypted drive, but they are usually accessible to authorized users. (The BitLocker to go reader is used to unlock an encrypted drive on a computer running Windows Vista or Windows XP.) )
Solution:
Decryption using the recovery key, if the recovery key is also lost, at least for a limited time is not cracked. Unfortunately, you can only reformat the disk partition.
Ensure that this recovery key is created the first time that BitLocker is enabled, otherwise you may lose access to the file permanently. If the computer has a Trusted Platform Module (TPM) chip, BitLocker will use it to seal the key used to unlock the encrypted operating system drive. When you start your computer, BitLocker asks the TPM to provide the drive's key and unlock it, and the following figure is the key recovery process: