Since i joined the crypto world i didnt face any problem regrading wallets but i see that many people lose funds...somtimes the situation is normal like when somone share his private key or back up phrase in a scam website...but lets imagine that somone open a nwe wallet on trust and start using it without even keeping the phrase...is there a way to enter his wallet and make transactions without even having the back up phrase?
You mean creating a Trust wallet account without backing up the wallet? I don't think trust wallet works like that. When you download the trust wallet app, before you can have access to the wallet, you either have to import a backed up wallet of yours or create a new one and back it up. That's how it works.
But, let's imagine that you didn't create a any backup at all, and if the wallet is stored on your device, no one can have access to it, since it is not an online wallet that you create with an email and password. If it's an online wallet that requires your email and password, then if someone gets your email they may hack into your wallet.