Hi, Julie.
This sounds odd but is hopefully easily resolved by logging into your site’s cPanel or FTP.
Navigate to yoursite/wp-content/plugins and see if there’s a plugin folder name of “the-events-calendar” — delete that and reinstall it via the wp-admin interface.
Of course, we always recommend restorable database and file backups as well as performing modifications first on a staging site before modifying anything on your live/production site.
Please let me know how this goes for you.