Q: Unable to restore from an encrypted iphone backup

There is no way to recover your information or turn off Encrypt Backup if you lose or forget the password.

About encrypted backups in iTunes - Apple Support

You need to restore your device and set up from scratch manually. You can also use the iCloud backup.

If you don't have your password:

• If someone else set up your device, check with them for the password.
• Try using an iCloud backup instead. If you don't have an iCloud backup, you can make one.
• If it's still relevant, try using an older iTunes backup.