WordPress Multisite blog doesn't work anymore

Hello there,

One of our blogs completely stopped working. Only the landing page is still accessible, but all other pages, sections (also the login page) etc seem to have vanished.

It concerns a blog that hasn't been used the past weeks, so we have no clue what caused this mishap. Since the blog is inaccessible, I cannot restore it to a previous back up.

It concerns: http://blogs.fasos.maastrichtuniversity.nl/afterbabel/20142015/

Many thanks,
Sjoerd