One time a similar thing happened to me. Try reverting all the changes or reverting to a previous version of your project, if you’re using version control. Though sometimes, even reverting doesn’t solve corruption issues (and sometimes it might not even be possible to revert) so I recommend always having a backup (preferably backups) of your project that’s not connected to any version controls.
Here’s a topic I found with a bunch of suggestions in it, check it out: Failed to load map! Umap appears to be an asset file
I really hope you’ll be able to overcome this issue! 
