The screen is asking for the BitLocker recovery key, which is a 48-digit key. If it is not showing in the Microsoft account already checked, the supported places to check are:
- Confirm the recovery key ID shown on the locked screen and note the first 8 digits. That helps match the correct key.
- Check the Microsoft account recovery key page again from another device: https://aka.ms/myrecoverykey.
- If the laptop was ever signed in with a work or school account, check that account here: https://aka.ms/aadrecoverykey, then go to Devices and select View BitLocker Keys.
- Check whether the key was saved in one of these other places when BitLocker was turned on:
- a printout
- a USB flash drive
- another person’s Microsoft account, if someone else set up the device
- If the device is managed by an organization, contact the IT department.
Important facts:
- Microsoft Support cannot retrieve, provide, or recreate a lost BitLocker recovery key.
- If the recovery key cannot be found, there is no supported way to unlock the encrypted drive.
- The remaining option is to reset the device using Windows recovery options. Warning: resetting the device will remove all files.