On my old computer, there was a data partition on the main disk that was encrypted with BitLocker. Since I haven't used this computer for a long time, I've forgotten the password. I've tried many possible ways to recover it, but none have worked. My question is: how can I recover lost data after forgetting a BitLocker password?
We need to remember a variety of different types of passwords, such as bank card passwords, email passwords, computer user passwords and disk encryption passwords (BitLocker password), etc., and for security reasons, we have to regularly modify the various passwords, which cause us to often forget passwords. If one day we lose or forgot the BitLocker password for a BitLocker encrypted drive, you can try the following solution to access your lost data.
If you have saved your BitLocker recovery key, you can use it to unlock the encrypted drive. Once unlocked, right-click the drive in File Explorer, select "Change BitLocker Password" from the context menu, and set a new password in the pop-up window.
If you cannot find the BitLocker recovery key, please refer to: What is BitLocker recovery key and how to find BitLocker recovery key?
To make it easier for users to locate and view BitLocker recovery passwords that are stored in AD DS, Microsoft offers BitLocker Recovery Password Viewer. Please follow the steps below to find your BitLocker Recovery Password.
If you've lost both your BitLocker password and BitLocker recovery key, the only option to retrieve your BitLocker password is to use a BitLocker brute-force cracking tool listed below.
If you can successfully find the BitLocker password or BitLocker recovery key using the above solutions, but still find that you have lost some files, you can recover data from the BitLocker drive with Hasleo Data Recovery.
Download, install, and run Hasleo Data Recovery. On the main interface, you'll see several recovery options. Please select BitLocker Data Recovery mode to proceed.

1. Please select the drive where you lost files, then click "Scan" to find all BitLocker-encrypted partitions on the device.

2. A pop-up window will appear asking you to enter the BitLocker password or 48-digit BitLocker recovery key. If you don't want to enter the password or BitLocker recovery key here, just click the "Skip" button to skip it.

3. Hasleo Data Recovery will display all detected BitLocker-encrypted partitions on the target device. If you provided the password or BitLocker recovery key in the previous step, the password status will show whether they match the partition.

4. Double-click the BitLocker-encrypted partition you want to recover data from. If you have previously entered a valid password or BitLocker recovery key, Hasleo Data Recovery will begin scanning for lost files. Otherwise, a prompt will appear asking you to enter the password or BitLocker recovery key. After entering the correct credentials, click "OK" to start the scan.

When the scanning process completes, you can filter and preview found files by path or file type. Once you've located the files you need, simply select them and click the "Recover" button to save them to your hard drive or another storage device. If some files are not found, click the "Deep Scan" button to initiate the Deep Scan Recovery process. While a deep scan takes more time, it can recover significantly more lost files.

Important Notes:
A: Yes, you can recover data from a BitLocker encrypted drive if you forget the password, as long as you have the BitLocker recovery key. The recovery key is a 48-digit number that was generated when BitLocker encryption was enabled. Without either the password or recovery key, the data remains encrypted and inaccessible.
A: You can find your BitLocker recovery key in several places: your Microsoft account online (if the drive was protected with a Microsoft account), Active Directory (if your organization uses AD DS), a printed recovery key document, or a USB drive that stored the recovery key when BitLocker was enabled.
A: If you've lost both the BitLocker password and recovery key, your options are limited. You can try using a BitLocker brute-force cracking tool like Passware Kit Business, Elcomsoft Forensic Disk Decryptor, or Thegrideon BitLocker Password Recovery. However, these tools require significant time and may not always succeed, especially for strong passwords.
A: If you can unlock the drive using the BitLocker recovery key, you can then change the BitLocker password to a new one. Right-click the drive in File Explorer, select 'Change BitLocker Password', and set a new password. This allows you to regain access without losing any data.
A: To prevent losing access, always save your BitLocker recovery key in multiple safe locations (Microsoft account, printed copy, separate USB drive), use a password manager to store your BitLocker password, and consider enabling automatic backup of recovery keys to Active Directory if you're in a business environment.