Q: app store wrong language

Are you in the right country store.   Check if the flag, bottom right (of a page in the iTunes Store) is your country, then click on the flag which will lead you to a page where you can select the right country.

If you are in the right country store but see the wrong language, take a look at the link below.

iTunes: Changing the display language

Big sorry, I wasn't sure which.   Could you use your computer (assuming you have one) and sync it to the phone?

What happens when you try this?

Open the App Store app, go to the Featured pane, swipe to the bottom, tap your Apple ID and sign out. Tap again and sign back in. The App Store will automatically change to the store from which your account is authorized to make purchases.

Helped me too

Helga