Quote from: sbl36912 on November 14, 2017, 11:57:45 AM

I bought bitcoin and stored it in ledger nano S since April , when the fork came and went on Aug.1st but never claimed bitcoin cash in my ledger nano s. Without any knowledge of bitcoin at the time, I sent my bitcoin to my new trezor hardware wallet on Aug. 14th.

This is good, this means your Bitcoins are safe from any untrusted Bitcoin Cash software.

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couldn't claim bitcoin cash on my Trezor.

Correct, your Trezor didn't hold any Bitcoin before the fork, so it doesn't hold Bitcoin Cash now.

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I'm wondering if I still can claim bitcoin cash on my ledger nano s if I sent it back.

DO NOT send it back! Bitcoin and Bitcoin Cash are two different chains. Step one after a fork is always to split your Bitcoins (to keep them safe), and you've done just this.

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Of cause , I have to buy a new ledger nano s and reactivate it since I gave it to someone with her new seed.( I still have my seed around) Thank you.

I don't have a Ledger nano s myself, but it seems to have a 24 word seed. You can most likely import the seed into https://iancoleman.io/bip39/. Read the Offline Usage notes on that page, and extract your private keys from an offline computer.

After this, you can pick any wallet from https://www.bitcoincash.org/#wallets, import the private keys that held your coins during the fork, and send them to a new address. I've only used Electron Cash by myself, other options should be okay too.

Take safety precautions:
Don't just trust any link that offers a wallet, download them from the official website.
Don't install untrusted wallets on your main computer, you never know what it might do.
Don't mix up Bitcoin addresses with Bitcoin Cash addresses, many people lost their coins sending it to the wrong address at an exchange.

After extracting your Bitcoin Cash, you can do the same for Bitcoin Gold in the future.