I forget the note password how to open those notes??

Hello,

There is unfortunately no way for you to recover the note without the password that was used to lock it.

If you forgot the password. You can create a new password, but this won’t give you access to your old notes. A new password will let you password protect any notes that you create going forward with the new password.

Here's how to reset your Notes password:

1. In the Settings app, tap Notes. Then tap Password.
2. Select the Notes account that you want to change, then tap Reset Password.
3. Enter your Apple ID password, then tap OK.
4. Tap Reset Password again.
5. Enter your new password and password hint. Tap Done.

Have a great day !

Alex

In addition to the info already provided, you should be aware that there is no “failed attempt” limit.

So just keep trying.

Also, you could have set a password hint; an option to display the hint will be presented after a few failed attempts.