My back up haze been gone???

hi yesterday I up dated my iOS for some reason I coul up date to iOS 10 so I should choose restore and updated but befor that I stored a full back up on my iTunes at 4 pm, finally after third time downloading and get nothing i could updated to iOS 10. After that I reconnect my phone to iTunes to get my backup but at the beginning iTunes synced I get the second backup at 1 am, and my last backup have been gone I went to backup list and I only saw two backup 1 am and 1:03 am wich were nothig of my stoge ( 2 or 3gb) , my fulll backup ( 55gb) wasnt even in the list, why???? now i lost everything, please help me there wqs all my detaled from last 2 years