

Sorry but unless you can re-create the original system it's BYE BYE. (As others have said)
I've re-iterated "Ad Nauseam" you should ALWAYS keep backup - especially of User Data - before doing anything major on a computer -- especially like replacing the OS.
Hopefully while not being the answer to your question you will have learned from this experience.
Imagine another time having say over 1 TB of irreplaceable Music files - and your disk gets broken / formatted erased etc etc.
Another scenario -- Pro Photographer doing a Wedding Shoot -- digital files get corrupted without a backup being available -- I'd hate to be the one to tell his Client / Customer.
Not nice.
Cheers
jimbo