Forgot iTunes Password - Recovery Menu
If you forgot your iTunes password, then don't panic. Just click on your username in the top right corner (or the sign in tab if it doesn't remember you) and then try to sign in. There's a button to the right of the password field that is labeled "Forgot Password?" Click on this button to bring up the next screen.
This one needs you to enter the username for the related account. As I said, this should just be the relevant email address. Type it in to pull up the next screen that's specific for your account. You have two options for recovery at this stage.
If you still have access to the email account, then you can have it just reset the password. iTunes will send a new link to your email address. If you click on the link, it will just reset your password to something new. Use this new password to log into your iTunes account and then bring up your account information again. Change the password to something that you'll remember and then call it a day.
If you don't have access to the email or don't want to go through the email reset process, you can have it ask you your secret question. It will first ask you to confirm a piece of account information, like your birthday, and then it will give you the secret question that you used when you signed up for the iTunes account. You just have to answer it to get your account back. Hopefully you can remember you secret question. If not, then you'll need to use the iTunes.
If neither of these works, then you will have to call iTunes support to try and find a human who can help you. If you have some other account details, then they might be able to help.
Hopefully these instructions should help anyone who forgot their iTunes password get their account back in order.