Somehow I have lost my Apple Store App

Use App Library to search Apple Store 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.

After my latest iOS 15.5 upgrade, the Iphone X "lost" App Store application - with A - ( not Apple Store) . In settings I can still see it, in App Library I cannot. When I tell Siri to use App Store , it says I don't have it - and asks to go to App Store. When I try to go to App Store, Safari sends a message that this is an error. I stopped by Geeks at BestBuy (and later Verizon) - they say they cannot restore App Store application on my iPhone (IPhone X, w/ iOS 15.5). W/o App Store I cannot upgrade several Apps (like Signal.org) and cannot download BitDefender Total Security. What are my options?