iTunes Restore Password is saying it's incorrect...

Apple won’t be able to help you with this either. You will not be able to use that backup unless you can guess or remember the password. There is no way whatsoever to reset the password to use that backup and Apple cannot reset it for you either.

You can reset the password to create another encrypted backup.

About encrypted backups in iTunes - Apple Support

Contacting Apple Customer and Support Service

1. Apple Store Customer Service at 1-800-676-2775 or visit online Help for more information.
2. Primary support help at Contact Support.
3. To contact product and tech support: Contacting Apple for support and service including international calling numbers.
4. For Mac App Store: Apple - Support - Mac App Store.
5. For iTunes: Apple - Support - iTunes.

If you can't update or restore your iPhone, iPad, or iPod touch

Get help with iOS update and restore errors

See if this helps: iOS- Troubleshooting backup issues in iTunes.