Hi there and welcome
I believe you are referring to the Roku Code, not Acorn as Acorn works off a username and password. As you reset the Roku, you need to activate it again
So go to your account here
And once signed in, you can enter in the activation code
Then to add Acorn
Search for "Acorn TV" within the Channel Store to add the channel to your Roku. If you are already an Acorn TV subscriber, you can use your regular email address and password ***** log in. If you are a new customer, you can sign up for a free trial or purchase a membership through Roku
Let me know please how you go.