Hello, thank you for reaching out to Microsoft Q&A.
You can locate the BitLocker recovery key in your Microsoft account at the following link:
https://account.microsoft.com/devices/recoverykey
If you are unable to locate the BitLocker recovery key, it is possible that the key is linked to a different Microsoft account of yours, or to a work or school account if you have added one on the device.
If you still cannot find the BitLocker recovery key and you need to reinstall Windows from scratch, you can perform a clean installation of Windows 11 using a USB bootable installation media drive.
You can use the Windows 11 Media Creation Tool (MCT) to create a bootable USB drive.
For reference, see: https://www.microsoft.com/en-us/windowsinsider/cleaninstall (Windows 11 Clean Installation Process – video link for your reference)
To boot your Surface from the bootable USB, see
Boot Surface from a USB device
Let me know if you still need more help.