iTunes Backup security code not working
Unfortunately there is no way to access a password protected backup without having the correct password (passwords are there for a reason). You can check if you have an iCloud backup available from your iPhone 5, but as far as the iTunes backup you won't be able to access it until you enter the correct password.

Apple specifically mentions that "There is no way to recover your information or turn off Encrypt Backup if you lose or forget the password", so you just might be out of luck on this one.

This page might help, good luck.