Hello Venkat!
The recovery key is a unique 48-digit code that is generated when BitLocker is enabled on a device. If you don't have the recovery key, the recovery key is saved on the Microsoft account signed-in on the Surface device. To find the recovery key, go to the Microsoft account website and sign in with the account. Then, go to the Devices section and look for the device in question. If the recovery key is saved, it will be displayed there.
Please let us know with how it goes.
Regards,
RodelioP.