I upgraded three blogs today to v2.6.5. The first two went flawlessly, and I got careless and clumsy with the third. I didn't make a complete backup and now, after the upgrade, none of the links work (including Pages, Archives, etc.)
Here's the blog: http://grandcruclasses.com/vineviews/
The careless mistake that I made was deleting my wp-config.php file. So I needed to generate new KEYS when creating the new config file. Could that have something to do with this?
All of the posts still exist when I login and attempt to edit. And even if i re-publish a post or click the VIEW THIS POST link in the editor, I get the 404 page. Worse, still, I'm getting the SERVER 404 page, not the WordPress 404 error.