Whoopee, my computer problems are sorted.
And as if to celebrate I had to drive slowly down the road from Serres while a whoopy (or hoopoe) walked in front of me, tucking into something delicious in the grass verge. It really is an amazing looking bird. I couldn’t take a photo, so I’ve grabbed a couple from the Internet. (Pity there is no agreement on how his named is spelt, but hoopoe seems the favourite.)
For those who know about these sort of things I had to deactivate cloud flare and my website host’s technical support changed the php version and deleted various security files. Et voilà,everything works again.