What should I do if the Win8 system forgets the BitLocker password?

First, let's take a look at using BitLocker Drive Encryption to help protect all files stored on Windows-mounted drives (operating system drives) and fixed data drives (such as internal hard drives). Files remain encrypted only when they are stored on an encrypted drive. Files copied to other drives or computers will be decrypted. If you share files with other users (for example, over a network), they will remain encrypted when they are stored on an encrypted drive, but authorized users can usually access them. (BitLocker To Go reader is used to unlock encrypted drives on computers running Windows Vista or Windows XP.)
Solution:
Use recovery key decryption, if recovery key is lost, at least limited Time is unbreakable. Unfortunately, you can only reformat the disk partition.
Ensure that this recovery key is created the first time BitLocker is enabled; otherwise, you may permanently lose access to the file. If your computer has a Trusted Platform Module (TPM) chip, BitLocker will use it to seal the keys used to unlock the encrypted operating system drive. When you start your computer, BitLocker asks the TPM will provide the key to unlock the drive and its lower figure is a key recovery process: