Equipment Return, never got letter stating what to return

Hello, I am trying to return my router after canceling my service but I never received the letter stating what I should return. I have been moving, you know how it is. I had fiber optics with the unlimited plan, I figure I should return the router and the power cord but should I return an Ethernet cable? It probably got mixed up with all my other Ethernet cables so I want to what type of cable it was if I have to return. Thank you.