Two days ago December 3rd, 2017 I was playing Forza 7 with a few friends to try and get the 356a from the forzathon. The game worked just fine, no problems, had all of my credits and cars and race suits, 21st birthday was on the 4th, and I hadn’t touched my Xbox at all that day (yesterday). Now it is December 5th, 2017. I go to log into Forza 7, excited to play with the new cars from the Doritos Car Pack, and the game goes straight to the intro movie and then the driver select. My game save is completely lost. The money, the hundreds of cars I had perfected and tuned, the driver gear and driver level, all gone. Yet I still have all the achievements. Not too sure how I can get any of this back. But I would very much like to have it all back. I worked hard for it. If anyone is able to help or if Turn 10 reads this, please contact me somehow? I would like to get it resolved. Thank you.
There are multiple posts about this on the front page. It’s happening to some people. There are some things you can try, but they aren’t guaranteed. Look through the existing posts.
Microsoft is fully aware of this issue. In fact, if you go to Xbox Support , you will see both Horizon and Motorsport are listed there as games with technical issues. They are working to fix both games. Just keep checking Xbox Support for updates
Well I’ve tried everything “tech support” could “help” me with. Not sure how the company will fix this for anyone but I’m hoping that happens. Sucks losing a couple months worth of progress.
So, for the first time ever I’ve got the same issue.
Hopped on yesterday after work, all excited to download the new car pack then bam! Intro opening played.
Back to zero. Was at level 225, played for 230 hours with 712 cars, all gone 
Emailed forzafb at Microsoft and also tweeted Turn10 and Forza for an urgent fix.
Doubt I will get a response per all the other customer feedback replies.
FINGERS CROSSED!