I never know my seed in the ledger device I have. Is there are a way to know the seed?
No, there is no way to display the seed phrase again after the initial set up. It does have a "Recovery Check" where you can input your seed phrase and it will confirm that you have written it down correctly, but it won't just display the seed phrase in plain text to you.
It's very risky to hold coins in a hardware wallet where you do not have the seed phrase. You are a single piece of hardware failure away from losing your coins. I would suggest that you move the coins out to a different wallet, reset the Ledger, back up your new seed phrase, and then return the coins to this new wallet.