Storyline 360 file is corrupted Help me to restore it.

Here is Articulate's standard advice: 

That is from this article about how to prevent corruption: Follow These Tips to Reduce Your Risk of Corrupting or Losing Project Files | Articulate - Community 

Unfortunately, if the above steps don't work, the file can't be saved. Ideally, you can update a recent backup version. If you don't have a backup, you'll have to redo the entire file.