Apple.com/recovery - resetting your Apple ID password can be done in several different ways such as answering security questions, using trusted devices, contacting Apple support team etc. The simples way to recover apple id visit apple.com/recover and follow the steps given here.
Apple ID Recovery Key. is a 14-character Recovery Key which is generated during the two-step signup process and is meant as a backup. If you forget your apple id password or lose access to all trusted devices and your phone number (but not both), the Recovery Key was the only way to restore your Apple ID account.
In case you know your Apple ID but can’t remember your Apple ID password, the Apple ID account page gives you 4 options how you can regain the access to your account:
Email Apple ID Password Recovery: Using this option, Apple will send a rescue email to your primary or secondary email address. You just need to follow the instructions inside to reset your password.
Apple ID Password Recovery with Security Questions: Another simple option how to perform Apple password recovery or iTunes password recovery is to answer your security questions. Unless you didn’t pay attention when selecting your security questions, you should have no problem with Apple ID recovery using this method.
Two-Factor Authentication Apple ID Recovery: To recover Apple ID password using two-factor authentication method, you need to visit apple.com/recovery and enter your trusted phone number. Follow the on-screen instructions displayed on the trusted device and change your password to a new one.
Two-Step Verification with Apple Recovery Key: if all else fails, you can dig up your Apple recovery key and recovery your Apple ID.
Most people use their email address as their Apple ID. This means that to recover Apple ID, you just need to try out all your email addresses. If none of them works, try going through your past iTunes purchases to see which account was used to make them.