If by “lock” you mean protect the contents of a D: drive from someone who does not have the encryption key, use Windows drive encryption where your edition and hardware support it. Simply hiding the drive letter or changing ordinary folder permissions is not equivalent to encrypting the data.
Use BitLocker on supported Windows editions
- Back up important files before changing drive encryption.
- Open the Windows BitLocker management controls.
- Find the D: drive.
- Choose Turn on BitLocker when the option is available.
- Select an approved unlock method.
- Save the recovery key somewhere separate from the encrypted drive.
- Follow the prompts to encrypt the volume.
The recovery key is essential
Encryption is designed to prevent access without authorization. If you lose every valid unlock method and the recovery key, your data may be unrecoverable. Verify that the recovery key is stored safely before relying on encryption.
Permissions solve a different problem
NTFS permissions can limit access between Windows accounts while the operating system is running, but they do not provide the same protection as full-volume encryption against someone who removes the drive or boots another operating system.
Check the Windows edition
BitLocker management features differ by Windows edition and device configuration. On a managed computer, follow the organization’s encryption and recovery-key policy.
Windows 10 normal support ended October 14, 2025.
Matt Jacobs has been working as an IT consultant for small businesses since receiving his Master’s degree in 2003. While he still does some consulting work, his primary focus now is on creating technology support content for SupportYourTech.com.
His work can be found on many websites and focuses on topics such as Microsoft Office, Apple devices, Android devices, Photoshop, and more.