Missing app
I just wanna update my whatsapp right, so the problem is i can not find or see it in App Store
Try this: Use App Library to search WhatsApp app, see this Apple article:
Organize the Home Screen and App Library on your iPhone
Organize the Home Screen and App Library on your iPhone - Apple Support
If you have find the app, tap & hold on the app, then drag to the Home screen & drop it.