I lost the calendar widget on my iPhone. "calendar" not found when searched for in apps library. Calendar still visible in iCloud. tried restored "calendars & reminders" ; powered iphone down & restarted.

It sounds as if you deleted the Calendar app from your phone. You will need to reinstall it. When you do, you will have access to the calendar widgets again.

See the instructions in this article:

Delete built-in Apple apps on your iOS 12, iOS 13, or iPadOS device or Apple Watch - Apple Support

Hello Techhelpwanted,

It sounds like you are unable to locate your calendar widget. We understand how important this is to you and we are here to help.

Are you attempting to add the widget by following the instructions provided here: Add widgets on iPhone

If the issue persists, can you provide a few more details? Which iPhone and iOS version are you currently using? Are you still able to add other widgets?

Also, when did you first notice this?

Cheers!