On an iPad you need to use the "iTunes Store" app. It has that exact name and it has not been replaced by Apple with the Music app on iPads. Both the iTunes Store app and the Music app should be on your iPad.
Try finding it with Search. See: Use Search on your iPhone, iPad, or iPod touch - Apple Support
Also note that apps can be removed from the Home Screen without being deleted. Go to the App Library (swipe left past your last Home Screen). From there you can touch and hold an app and slide it to the Home Screen.
If it was deleted, see the following from Delete built-in Apple apps from your iPhone, iPad, or Apple Watch - Apple Support
Restore a built-in app that you deleted
- On your iPhone, iPad, or Apple Watch, go to the App Store.
- Search for the app. Make sure that you use the exact name of the app.
- Tap the Redownload button
. - Wait for the app to restore, then open it from your Home Screen.