How do I recover my backup password

If you are being asked for a password, a password was set up by you, even though you might not remember doing this.

Unfortunately, Apple does not store the password. It is up to you to remember it or write it down.

Sorry, no workarounds or back doors here.

About encrypted backups on your iPhone, iPad or iPod touchApple SupportOfficial Apple Support › en-in

I'm going to assume this is using your computer with either iTunes (Windows) or Finder (Mac). Computers can't create passwords on their own, and yes, you had to have created a backup password at some point. The good news is you can guess as many times as you want, but until you guess the correct password, you won't be able to access the backup. You can create a new backup (assuming your phone isn't damaged) and make sure to turn off the option to password protect the backup. Otherwise, there's nothing anyone here or at Apple can do to help you with a Password locked backup.