Your site appears to display fine for me. Did you add this custom CSS through a plugin?
No. I added a custom.css file with a FTP client.
The site does display as the 2013 theme should, but I had a lot of custom css in the custom.css file, which has gone. It looked nothing like that 2 days ago, last time I checked it.
It did update to WordPress 4 – but that was last week.
I don’t understand where it’s gone. The header.php file has also removed the link to the missing custom.css.
It’s as if the whole thing was deleted and reinstalled – which I did not do.
Unfortunately, that’s what happens when you update a theme. You lose all changes to theme files and any files you added to the theme’s folder are removed. That’s why it’s recommended to either use a custom CSS plugin or a child theme to modify your theme.
Your hosting provider may have a backup of your custom stylesheet. I would contact them and ask.
This did not happen after the update. And I have several other sites which have not been erased like this.
I will try the host.
Are you sure you didn’t upgrade Twenty Thirteen? According to your site’s stylesheet, you’re using version 1.3, which was released last week, around the same time that WP 4 was released.
Yes, I just saw that. I didn’t. But it might have been done by someone else. I bet he did, in fact. That would make sense. Damn it.
I don’t suppose WP keep a backup anywhere? I’ve raised a ticket with the host, but it would be handy if there was an archive somewhere in the public_html, perhaps?
Lesson learned. Make back up. That was a week’s work.