This plugin doesn’t work at all

Suddenly this plugin just doesn’t work. When I wanted to create an event page, when the page was finished and I started going to the online view, it turned out that the page was not found. There is only a 404 Page Error page. Whereas previously it was normal, and I had absolutely nothing to change.

I thought it would take a while, but it still doesn’t work. And some of the events pages that I created, all disappeared, couldn’t be found anymore. Every time I create the event page, it always gets an error, what I have made is erased again. Please repair the damage immediately, because it is very necessary. And please respond