I have deleted the app store . How do i get it bac

You cannot delete the App Store app on your phone. If you could, you would be rendering your smartphone to a phone only. You may have restricted it in screen time. Take a look at this.

Use parental controls on your child's iPhone, iPad, and iPod touch - Apple Support

If you didn’t restrict it, it may be hidden in a folder. Do a search for it. If it is in a folder, the name of the folder will appear to the right of the app icon.

Use Search on your iPhone, iPad, or iPod touch - Apple Support

Check settings, screen time, content and privacy restrictions, iTunes and App Store purchases, allow installing apps.