Probably a stupid question but

How do l access the apps on the screen? l've tried everything and it's just not there. l used to get it by pressing the phone icon on the rhs and then pressing the icon that looked like a lego brick (bottom right of screen)

But now that doesn't work. The lego brick doesn't appear and it just goes to the phone display.
There must be an easy way to do it but l can't find it.

Also l can no longer stream from Spotify and the option to use Google Maps rather than the built in nav has disappeared

The phone is still paired and l can make and receive calls.

EDIT

I had inadvertently turned off Apple Car Play in the menu.