Calendar deleted after update

If you have iCloud managing your Calendar iPhone will automatically sync

the content.

Normally update do not delete content.

But if you don't have iCloud for your Calendar events and you

delete it then it's gone.

Do you have a computer?

If you do goto https://icloud.com/calendar/

Login using your Apple ID and password

If it's empty then it's gone, if not it will automatically sync with your iPhone,

make sure it's connected to the Internet.

If you are in iCloud.com you can try using Data Recovery and

see if you have anything there.

iOS update do not delete Calendar.

Do you have iCloud managing your Calendar?

Or is Calendar app missing after the update?