The politicians are completely out of touch with the public (politicians don't know how the public feel because they never ask them!)
I've been living abroad and am completely out of touch with what's happening in the UK at the moment.
He's out of touch with reality (this suggests a more serious mental problem!)
It can also be used to mean that you haven't been in contact with someone for a while:
Since he left London, he's been totally out of touch (though normally we would say "he hasn't been in touch at all")