Hey there vanja80,
We understand that you're not seeing the Youtube app on your iPhone and there are also issues with the connection to the iTunes Store. We'll be happy to help.
It's certainly possible these two issues may be related. With that in mind, we'd like, to have you start with the steps here: If you can't connect to the App Store, iTunes Store, or other Apple services
This will guide you through a few things to check and steps to take.
If the issue persists, let's make sure the app is available in your region. You can do that using this link: iTunes Link Maker
Make sure to switch to your region and change the Media Type to "iOS Apps".
We hope this helps!