If you cannot boot into Windows, you must use the recovery environment:
BitLocker Drive Encryption (BDE) stands as a cornerstone of Windows data security, designed to protect information by providing encryption for entire volumes. At its core, the "BDE unlock" process is the critical bridge between encrypted, inaccessible data and a functional user environment. This process is not merely a password entry task; it is a sophisticated cryptographic handshake involving hardware security modules, recovery protocols, and organizational policy. bde unlock
That’s your BDE unlock.