Hello Dams59,
First, I checked all the delivery options for each of the products of my store.
They were not all set up correctly, as I made some changes in delivery options and did not update the corresponding options in my product pages.
But this was not my only mistake, so if it still does not work, you probably should look at the operations you made on your server. Did you do an upgrade or update ? Onmy side, I had to re-load my full site, but I did not remove the .opcache file, which I should have done.
And last, I had a bug coming from my Mailchimp plugin. A freelance developer identified it and simply de-activated this module.
Now my website works fine, but the Mailchimp automatic synchronisation is not running.
Good luck with your problem.
What is the url of your website ?
Cheers