Try going into settings>itunes and apps store>tap on your AppleID in blue at the top>sign out. Make sure you know your AppleID and password before doing this. If you are unsure, go to appleid.com and try and sign in. If you cant, then you can try and reset it (Follow the steps in the link under this) Then once you are signed out, restart your phone, and go back to the itunes and App Store settings and sign back in.
Thank you for the reply. I signed out, restarted and signed in again. Still when double click (tap) on sidebar, nothing happens (just bounces).
Found the issue... The double click is for the sleep/wake button, not the screen. I was double clicking on the screen. Maybe is just me, but this seems to be an unclear notification...
can’t download apps
