Okay, I decided to update some plugins, but I only updated three inactivated plugins. I did this through the WordPress Admin page. This seemed to work fine, although the installation page didn't reload, showing the installation of the new update was completed.
When this was done, I went to a page run by another plugin (Sermon Manager), which I haven't touched throughout this updating process. And I checked it just previously, and found it working, as expected. This time, though, I got the 404 error, for every page hosted by the plugin. The posts are there in the SQL database, I checked that. The plugin seems to work just fine in the Admin page, so there's no indication of anything being wrong. But WordPress cannot find the pages and posts!
But every other page and post works just fine, including pages and posts owned and run by another plugin (Events Manager).
This is just very weired, and I cannot really find out any solution! Need help ASP!!!
Webpage: http://www.evangeliska.nu
example of crashed page: http://www.evangeliska.nu/sermons
Thank you for your time
/Christoffer