If you sent the BTC to your nano, it's likely that somebody replayed the transaction onto the BCH network, unless your ledger was using a segeit address.
That's actually impossible... BCH has full 2-way replay protection... BTC transactions are not valid on BCH network... BCH transactions are not valid on BTC network.
To get your BCH: Download Electron Cash (a Electrum fork for Bitcoin Cash), import your old Electrum wallet and send your BCH to your Nano S Bitcoin Gold address.
errrr... I really hope you meant Bitcoin CASH address!! haha... Man, so many "Bitcoins"... gold, cash and now diamond... getting confusing!
![Tongue](https://bitcointalk.org/Smileys/default/tongue.gif)
In any case, I'm pretty sure that you CAN'T accidentally send to a BTG address... they changed the address format, so it SHOULD get rejected.