If you need to recover an encrypted volume from a Windows or MacOS desktop and you are using Sophos Central to mange your endpoint protection, you can do the easily through the Sophos Central Interface.
Login to Sophos Central at the sophos.com website.
From the Sophos Central Dashboard, Click on Encryption in the left hand panel.
On the left Click on Computers.
Select the Computer that needs to be recovered from the list.
Scroll to Device Encryption in the new screen.
Select Retrieve Recovery Key.
The Retrieve Recovery Key will appear in the pop-up window.
If the key displayed does not work, perhaps you renamed a computer or a drive was moved around at some point. You can search for additional recovery keys here as well.