How can I retrieve my cakendar

[Minnow20]

It is the default calendar on my iPhone. It is still on my iPad.

 

[Ralston18]

Did you have the iPhone and iPad synced before?

You may need to re-sync per the following link:

https://tunesgo.wondershare.com/iphone-transfer/iphone-calendar-not-syncing.html

Overall, more information is needed. Do you receive any error messages? Can you provide additional explanation and description? Thanks.