My savegame has crashed?

I’m sorry for my unskilled English because I am Japanese.
Yesterday when I booted up Forza Motorsport 7 in my PC, the title screen displayed a message like this: “Loading error: an unknown error occurred” and the game didn’t start.
I thought it was a software problem and I reinstalled the game 2 times but it didn’t work.
After that, I reset the game from Apps & Features and booted up the game without cloud storage synchronization. Then the game started with the opening movie.
I think it means that the savegame in cloud storage has crashed. I might be able to play the game but I must discard my savegame and I don’t want to do it if I can.
I can’t do anything anymore… there is too little information in my country Japan, so I came here. Could somebody tell me how to fix the problem?
Best regards.

If the cloud save is corrupted and you have deleted your local save there is nothing you can do except start over. Sorry.