How to recover encrypted password

I recently completed a back up to my itunes on my laptop. Today i have tried to restore back up onto new iphone as i have previously done many times but their seems to be an encrypted password in place which i must have set a long time ago. Is there a way to recover this as i have tired every possible password i would use and nothing works.

i have recovered most data from an icloud back up but no photos and videos were on this.

Help please....