Good morning David and welcome back!
Thank you for reaching out to us.
We are sorry to hear about the calendar disappearing on you.
I would love to help you with this topic.
The message means that you need to update the Events Calendar, not install it from scratch.
The good news is that there are 2 simple ways to fix this:
- To be safe, make a database backup
- Head over to Plugin > Installed Plugins
- Try to update the Events Calendar plugin
- If that does not work, deactivate and completely delete the the Events Calendar plugin
- Once that is done, try reinstalling it again
Let me know how that goes.
Best regards,
Geoff B.