how do i reinstall the apple store app on my iphone 6s plus

If you mean the Apple Store app where you can buy hardware like computers and iOS devices, and not the App Store where you can buy and download Apps, then the Apple Store App can be downloaded from the App Store App.

The Apple Store App icon is not a suitcase, its a shopping bag.

The App Store App: cannot be deleted, so make sure it was not moved to another screen, or is restricted in Settings->General->Restrictions->Installing Apps.

App Store

2 different Apps, for 2 different purposes.

To add to the confusion, I actually have no idea what you mean by this:

Singinglady4 wrote:

Also, I don't care to use the app through FB or Twitter.

Use the Apple Store app through Facebook? Twitter? I have no idea what this means.

The Apple Store app (which looks like this):

... is available in the App Store. Here is the address (applicable in the U.S. App Store):

https://itunes.apple.com/us/app/apple-store/id375380948?mt=8

Hopefully you're certain you're asking about the Apple Store app, and not the iOS App Store or something else.

The Apple Store app changed to the suitcase perhaps six or eight months ago.

You're welcome.