How do I reinstall accidentally deleted App Store on my iPhone 6?

Are you in the EU? It is only possible to delete the App Store if you are in the EU. Otherwise, it will not be on your screen for either of these reasons:

• It is in the App Store and you can swipe left on your screen until you reach the App Library and place it back on your Home Screen.

Find and use your apps in App Library on iPhone - Apple Support

• Screen Time Restrictions have been set. If you are on a Family Plan, then the Organizer can control your Screen Time settings, otherwise you can do it on your device at Settings > Screen Time > Content & Privacy Restrictions > iTunes & App Store Purchases > Installing Apps.

“Accidentally deleted the App Store.: Accidentally deleted the App Store from my iPhone 6. Need to reinstall. Please advise.”

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Getting App Back:

Use Drag & Drop on the Home Screen:

Tap on the Home Screen. Then, hold your finger on the far-right edge of the screen. Next, swipe your finger in from the right. Next Drag & Drop the app back over.

“Accidentally deleted the App Store.: Accidentally deleted the App Store from my iPhone 6. Need to reinstall. Please advise.”

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Get App Sore From from the App Store Online:

If you can’t get it back through Drag & Drop, then, using a Web browser, get it here: App Store - Apple