Problem phenomenon:
A lock icon is displayed on the drive. The system image is backed up to an external storage device, and a BitLocker recovery key is required when booting from a USB drive. After restoring the system, a 48-bit recovery key is required to unlock the hard drive.
Problem causes:
Your device has been taken over by BitLocker's Drive Encryption. This is Microsoft's new protection strategy to ensure that your data will not be leaked if your device is lost.
Solution:
1. To get started, open the "Start" menu, search for "Control Panel" and select "Control Panel" in the search results.
2. When Control Panel opens, click "System and Security".
On the "System and Security" page, choose "BitLocker Drive Encryption."
4. Next to the drive where you’ve enabled BitLocker, click "Turn Off BitLocker."
5. Select the "Turn Off BitLocker" option.