Good evening John and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
We are sorry to hear about your calendar disappearing on you!
I would love to help you with this topic.
As a first troubleshooting step, could you please provide us with your complete system information in a private reply using the instructions found in the following link?
https://theeventscalendar.com/knowledgebase/sharing-sys-info/
There are also additional steps I would recommend taking.
Head over to Events -> Settings -> Display and change the setting for Events template.
Once that’s done, re-save your permalinks under Settings > Permalinks
Let me know if that helps.
Have a great day!
Geoff B.