We can reply here. In this case, it looks like your website is down at the moment, which wouldn’t be caused by a change in some API settings. If you cannot access your WordPress dashboard, you could log in to your web host’s control panel and rename the wp-content/plugins folder. This will force deactivate all plugins, which will allow you to access your site’s dashboard again. Once you’ve regained access, you can change the /plugins folder’s name back.
At that point, it’s advised to delete the Event Espresso plugin, and reinstall a fresh copy. You can download a fresh copy of the Event Espresso plugin from your account page.