After a cloud sync on pc my save data is gone, ive tried reinstalling the game and everything to no avail, i also contacted xbox support which got me nowhere.
Welcome to Forza, where dreams are lost forever in the ether!
I used to be able to help people like you, but since they removed certain functionality from the game i can no longer do that.
All i can offer you is a link to their support site, submit a ticket and hopefully they can give you some credits and cars in about 5 weeks when they get to your ticket!
https://support.forzamotorsport.net/hc/en-us