Help - wordpress blog doesn't load completely


I set up WordPress on my partner’s site the other day, and he was happily blogging away on it with no problems, but now all of a sudden today only the site header and top menu will load - the posts, sidebar, etc. just don’t show. They’re there, though, in the sql database/admin panel/etc. This problem does not seem to be theme-specific - I changed the theme back to the default Wordpress, and the same thing. As these few steps have just about effectively tapped out my troubleshooting skills when it comes to this sort of thing (I’m new to WordPress, and not exactly an ace with web programming, either), I’m hoping someone here can point me towards what needs to be fixed.

Thanks in advance for your help!!!