It’s fixed! I did finally get the host tech team to help me. The basic problem was that ‘localhost’ was not the address to use. I found the correct address in my database management control panel. To compound my problem, I had made a mistake in my database user name (one that I missed after checking it umpteen times.)
Now to learn more of the wonders of WP.
Thanks, Esmi, but the host will not help, saying they do not provide technical support for WP.