My WhatsApp icon is missing

using iOS 14?

From your Home Screen, swipe left until you get to the App Library.

Swipe downward and you'll get an alphabetical list of your apps.

Locate the app in the list or type the app name into the search field

Once you've located the app, tap/hold until it raises/selects, then drag it and it'll pop out to your Home Screen

Organize the Home Screen and App Library on your iPhone - Apple Support

You should have told us which iPhone and iOS version you were using so that answering your question could have been easier. I am going to assume that you are using iOS version 14.4. to answer your question.

If your WhatsApp is still on your iPhone and not on your home screen then it is probably in the App Library which is the last page when you continue to SWIPE LEFT until you reach it. Once in the App Library then you can check in the Social folder and find the WhatsApp app. Once found then you can Touch, Hold and Drag it out of there and place it on the home screen of your choice.

Axel F.