How to reset laptop with having the pass key

Because this is a found laptop, return it to its owner or hand it to the location where it was found or local authorities; do not erase it or attempt to access the owner’s information.

If ownership has since been legally transferred to you, the available options depend on which key prompt appears.

If it requests a 48-digit BitLocker recovery key

The previous owner must retrieve the key from the Microsoft account, work/school account, printout, or USB drive where it was saved. Microsoft Support cannot retrieve, recreate, or bypass a lost BitLocker recovery key. The first eight digits of the displayed recovery key ID identify the required key.^1^

Because the previous owner’s account remains associated with the computer, ask them to either:

• Recover the key and unlock the device, then properly remove their account and reset it; or
• Confirm that you may erase the entire drive.

Since the built-in reset has already failed at the key prompt, do not repeat it. If the key is unavailable and you are now the legitimate owner, the supported alternative is a clean Windows installation, which permanently deletes the previous owner’s files, accounts, applications, settings, manufacturer customizations, and encrypted partitions.^2^

Clean-install Windows after ownership is confirmed

Warning: These steps erase the internal drive. Do not proceed merely because you physically found the laptop.

1. On another working Windows PC, connect a blank USB drive with at least 8 GB. Everything currently on that USB drive will be deleted.
2. Open Microsoft’s Windows installation-media page, select the Windows 10 tab, download MediaCreationTool.exe, and use it to create the bootable USB.^3^
3. Connect the USB to the laptop and start it from the USB. The key used to open the boot menu varies by manufacturer, so consult the laptop manufacturer’s instructions.
4. Start Windows Setup and choose a custom/clean installation, not repair or reset.
5. At the drive-selection screen, delete each partition on Disk 0 until only Disk 0 Unallocated Space remains. Do not delete another disk if more than one is listed.
6. Select Disk 0 Unallocated Space, continue the installation, and complete the Windows setup.
7. If Setup requests a product key, the correct key or digital license is required. Many devices have a matching key stored in firmware and apply it automatically, but that is not guaranteed. Install the same Windows edition previously licensed on the laptop.^2^

Windows 10 support ended on October 14, 2025. If the hardware supports Windows 11, install Windows 11 instead; otherwise, continuing with Windows 10 leaves the computer without regular free security fixes.^3^

If the prompt appears before Windows starts

If it is a BIOS/UEFI, administrator, or firmware password rather than a 48-digit BitLocker key, reinstalling Windows may not remove it. Contact the laptop manufacturer and provide proof of ownership. There is no supported basis for bypassing a firmware security password on a found device.

References

1. Find your BitLocker recovery key
2. Reinstall Windows with the installation media | Microsoft Support
3. [Windows 10](https://support.microsoft.com/windows/deployment/install-upgrade/create-installation-media-for-windows)