Q: iPhone back up - PLEASE HELP?!

Hi,

So I recently had to replace my iPhone 6 as the screen smashed and it was bent meaning a replacement screen could not be fitted. The replacement handset is on an old software (iOS 8.4?) so when trying to restore from back-up it asked me to set the phone up as a new iPhone, update the phone to iOS 9.2 and then restore from back-up.

I did as it said as I was rather keen to get my new phone to exactly as the old one was, but as soon as I set it up as a new iPhone it backed it up to my iTunes and now I cannot find the back-up I did earlier meaning that I will now have to start from scratch. Any apps, message threads, contacts etc. are lost.

Is there now anyway I can get that back-up back? Or do I really have to start as though I never had these back-up's.

Many thanks in advance for any help.

Rory.