You have a server named Server1 that runs Windows Server 2012 R2.
Server1 has a single volume that is encrypted by using BitLocker Drive Encryption (BitLocker).
BitLocker is configured to save encryption keys to a Trusted Platform Module (TPM).
Server1 is configured to perform a daily system image backup.
The motherboard on Server1 is upgraded.
After the upgrade, Windows Server 2012 R2 on Server1 fails to start.
You need to start the operating system on Server1 as soon as possible.
What should you do?

A.
Start Server1 from the installation media. Run startrec.exe.

B.
Move the disk to a server that has a model of the old motherboard.
Start the server from the installation media.
Run bcdboot.exe.

C.
Move the disk to a server that has a model of the old motherboard.
Start the server. Run tpm.msc.

D.
Start Server1 from the installation media. Perform a system image recovery.

Explanation:
Encryption keys are lost. Nothing mentioned about password/keys recovery.
My point is that the only way is to restore the server from a backup.
http://social.technet.microsoft.com/Forums/windows/en-US/6b34b4da-b1e2-4038-8d6d192f973cadea/usingsystem-image-with-a-bitlocker-system-drive