Yes you can never change your password and you can only access it if you have the private key . But its sad if there are coins inside so you better save your private keys always to prevent such thing if you think you been hack then there is no other way than creating a new one
If anyone will lose his password, he can use his private key to open his wallet and that is the last resort that he has. If he lost that one also then better forget that one because there is no other way you can access your wallet anymore. Next time be careful with your password and private key and you should not lose it.