My iPad doesn’t have App Store app

Have you tried searching the iPad for the app?

Search on your iPhone, iPad, or iPod touch

If necessary, do a backup and try a factory reset. Then restore from your backup.

Restore to Factory setting.      

Backup - Restore your device from an iCloud or iTunes backup.      

If you want to restore backup, click the last line in my post for instructions on how to restore. If you don't want to restore a backup, what do you want to restore?