How do I sign in iTunes and App Store

I can’t connect to app store and sign in iTunes and app store

You need to have a good Service and/or Wi-Fi.

If they are On, turn Off Hotspot & VPN.

Charge the battery > 70%.

If you can't connect to the App Store, iTunes Store, or other Apple services

If you can't connect to the App Store, iTunes Store, or other Apple services - Apple Support

-> If you tried all of the above steps and you still can’t connect, contact Apple Support.

iPhone 6, iOS 12

I can’t use any apps in my phone

What do you mean?

Do you mean you cannot download apps?

You have an outdated iPhone.

Outdated iPhones are not eligible for an iOS update, for example: iPhone 3 / 3G / 4 / 4S / 5 / 5c / 5S, 6 , 6 Plus.

iOS 12.5.7 is the latest iOS security update for iPhone 5S, 6, 6 Plus.

Go to Settings -> General -> Software Update -> Download and Install (if you haven't already done that).

iPhone 5S, 6, 6 Plus can’t be update to a higher iOS (13 and later). 

If you have an outdated iPhone that cannot be updated to iOS 13 or later, many apps will not be able to download.

Outdated iPhone no longer meets the requirements for many apps.

Most apps require iOS 13 or later.

Considering a newer type of iPhone?

Read this before you buy a newer type iPhone.