This is referring to Argent X (browser extension recovery). If you want to prepare for your Argent mobile wallet recovery, please find the details here.
Recovery with seed phrase
You can find the seed phrase if you click on Settings icon in the top-right corner > Setup your account recovery (if you never set it up).
Once you save your seed phrase once, you can later find it in Settings (gear icon in the top-right) > Show recovery phrase.
Recovery with private key
It is impossible to recover your Argent X wallet with the private key.
If you have lost your seed phrase and have a private key only, you can try a CLI tool created to move assets from the lost wallet to a new one.
Here you can find a guide on how to use CLI tool for Windows and Mac computers.
Advanced security setup
You can setup Argent Shield as your Argent X account (not entire wallet!) guardian for the occasion that you lose your seed phrase.
You can find more details on escape mechanisms here.
Password/json file option for very old wallets
The early wallet users might have access to the recovery of their Argent X wallets via starknet-backup.json file in combination with your Argent X password. You will need to recover your wallet via seed phrase or advanced recovery options if you forget the password or lose your .json file.