i would like to have itunes back on my iphone .

There has never been an app with the name "iTunes" on iPhones.

There is an "iTunes Store" app and an "iTunes U" app.

If the iTunes Store app was deleted, you can use the instructions in Delete built-in Apple apps from your iPhone, iPad, or Apple Watch - Apple Support to reinstall it.

Redneckangaroo wrote:

I have always been able to access my Itunes music from my iphones . and not through the MUSIC app .

...

What app did you use?

It wasn't any app named "iTunes."

The app normally used is the Music app.

The original iPhone (2007) had the "iPod" app and the name was changed to the "Music" app in 2011. The "Apple Music" streaming service started in 2015.

Ever since 2015, the Music app is used both for the streaming service and to listen to your own music. You do not need to subscribe to Apple Music to use the Music app to listen to your own music.

Also see the following from Get music on iPhone - Apple Support

Use the Music app  to enjoy music stored on iPhone as well as music streamed over the internet.