If you have forgotten your password, you can reset it from the "Forgot Your Password?" link (https://accounts.nintendo.com/password/reset) that can be found on the Nintendo Account sign in page.

Note: You will not be able to perform the steps to reset your password if you no longer have access to the email address used to create your Nintendo Account. If you are signed in, you can reset your password using the Change Password service.

If your Nintendo Account was linked to another account during registration, please follow the appropriate procedure for that account.

If your account is linked to an NNID, you will need the password for the NNID. If you have forgotten the NNID password, you can check it here: https://id.nintendo.net/login