If your BitLocker external hard drive won't accept your password or recovery key, even if they are correct, consider accessing it from a third-party BitLocker recovery tool.
iBoysoft Data Recovery for Windows has a dedicated "BitLocker Recovery" section you can use to unlock the BitLocker drive and restore its data. This software is compatible with SSDs, HDDs, SD cards, USB flash drives, and other storage devices on Windows. You can follow the steps below to access your BitLocker-encrypted drive:
Step 1: Download and install iBoysoft Data Recovery for Windows on your PC.
Step 2: Launch the BitLocker recovery software, select your BitLocker drive, and click Next.
Step 3: Enter your password or BitLocker recovery key and click OK.
Step 4: Preview the files after the scan is complete.
Step 5: Recover those you want back.