It looks like I got it running. I replaced the functions.php file in my theme with the one from twenty thirteen and it worked. So I went line by line to isolate which bit was working. It’s this line:
‘add_theme_support( ‘post-thumbnails’ );’
I’m so happy to find this. However, I would love to understand it. Does anyone know why this worked? And, more importantly, does it have any potential for adversely affecting my site?
Thanks so much, Tara, for your help.