My site got hacked earlier today, courtesy of the big gaping security hole that turned up in Joomla! 1.5 a few days ago. Normally I'm quick to apply such security updates, but I had a few other updates in mind too so I was putting it off for a few days. Getting hacked is a new experience for me, so that'll teach me to be so casual in future! It will also teach me to make backups more often, but fortunately the data hadn't actually been deleted. I found all the articles were still in the database only with the state field changed to -2, so if anybody else falls victim to this same attack (it seems to be scripted so there are probably quite a few), you can fix your database as follows:

UPDATE `jos_content` SET state = 0

...which should restore all the articles to the list having "unpublished" status, so you can then re-publish from the administration interface as required.

The attack to which I'm referring leaves a single published article having the same title as this and displaying the following unpleasant image: