You have to send all your coins out to a temporary wallet (like coinbase) and set your Nano up as a new ledger.
It was one of the questions I looked up before I bought it, and something you should do right away, imo. If you lose your key your stuff's gone otherwise. Permanently unless you find it and remember your pin.
I think you can reset the Nano 24 word passcode but forgot believe you need the passcodes to do so. You need to order a new Nano and transfer your XRP on to that one because if you lose that Nano your screwed. Make a note to order a new one like yesterday.