@LunaSchteingart - I'm very sorry this has happened to your story. Please contact Esri Support and they will help you fix this issue.
There have been a very small number of people affected by this issue, and in every case we are aware of our Support team has been able to recover the story.
We are actively looking into this issue so we can address the root cause. Since the impact of the issue is that you are unable to use/edit the story this is a high priority for us.
Owen Evans
Lead Product Engineer | StoryMaps