In case of loss or theft of your Ledger Wallet - or at any time - you can restore your entire balance either
thanks to the 24 words you copied on the Recovery sheet. These 24 words are paramount, they are what provides you the ownership of your coins. You must never reveal them, and never loose them.
Without the PIN code (and the second factor card for Nano and HW.1), a thief cannot access your bitcoins. If you have any doubt about compromise of your PIN code and/or second factor card, you should immediately transfer your balance to another wallet.