how to reset password using firebase code example

Example 1: firebase forget password

It sounds like you're looking to send a password reset email. See this example from the Firebase documentation:

FirebaseAuth.getInstance().sendPasswordResetEmail("[email protected]")
    .addOnCompleteListener(new OnCompleteListener() {
        @Override
        public void onComplete(@NonNull Task task) {
            if (task.isSuccessful()) {
                Log.d(TAG, "Email sent.");
            }
        }
    });

Example 2: reset password firebase auth

var auth = firebase.auth();
var emailAddress = "[email protected]";
auth.sendPasswordResetEmail(emailAddress)
.then(function() {  
// Email sent.
})
.catch(function(error) {
// An error happened.
});