How can I retrieve lost Calendar Events on iPhone 12 Plus?
iphone 12 plus:
Calendar events disappeared! I don't think I updated any software. It was there, then gone. How do I get my life back???
[Re-Titled by Moderator]
iPhone 12 Pro Max, iOS 17
The answer depends completely on exactly where the calendar containing the events is housed. This is shown in Settings > Calendar > Accounts > [the (hopefully) one account containing your calendar].
It may well be these events are gone forever.