Hello,
If your system is asking you for your BitLocker recovery key, there are several places that your recovery key may be located, depending on the choice that was made when activating BitLocker. If you saved the key to your Microsoft account, you can access it by going to https://account.microsoft.com/devices/recoverykey. If you printed the key, it may be with important papers related to your computer. If you saved the key to a USB flash drive, plug the USB flash drive into your locked PC and follow the instructions. If your device is connected to a domain (usually a work or school device), ask a system administrator for your recovery key.
If you are unable to locate the BitLocker recovery key and can’t revert any configuration change that might have caused it to be required, you’ll need to reset your device using one of the Windows recovery options. Resetting your device will remove all of your files.
Let me know if this helps or we can explore other options.
Cristiana