registration page not found

I downloaded the plugin yesterday and was working perfect! I loved it, but today I accidentally deactivate the plugin. when I active it again. it still show me my event list but when I click on it to see all the details and register, it says me “Ooops, page not found”.
what should I do?
I tried also to add a new events but still same problem

https://ww.wp.xz.cn/plugins/quick-event-manager/