We have seen a rash of websites attacked and essentially destroyed recently. The attack is poorly executed and fills the website with enough garbage to cause it to be unable to run. The sheer number of files that are placed in the folders and the code changes make it impossible to clean. The website has to be reuploaded from the original files.
Therein lies the rub. We suspect that many of our clients do not have a backup copy of their website. It seems that generally web developers do not provide a copy. If your website was created recently (perhaps the last couple of years) then the developer can probably provide a copy to you. If not, then we should download a copy from your live site now and place it in your office for safe keeping.
Websites are pretty easy to attack because they often sit in their original state for many years without updates and the servers that they sit on are often not updated either.