Is it possible to hack the xml/flash/php guestbook?

I have been using the xml/flash/php guestbook on a site for over a year now with absolutely no problems. In the past week or two though, all of the entries (about 25-30) have been erased. Did my host erase my data, or is it possible to exploit the scripts? All files (.swf, .xml, and .php) are still on the server, but the xml file is completely blank.