My Database has been deleted (but not by me..)

Hi,
I recently set up my blog http://www.safetan.com.au/blog/ and had everything working o.k. The other day I went to the URL and had an error message “It doesn’t look like you’ve installed WP yet. Try running install.php”. As I couldn’t logon etc., I ran the install, and found I had to re-enter all my information and set-up. Everything once again worked fine. Now today I have gone to check on things and have come across the same error message. I’ve checked back in through myPHPadmin where my database is, and all the tables and data that were there the other day have been deleted. As I haven’t deleted them, I’m wondering if anyone can tell me if there is some kind of script error that could have erased this. I’m not a programmer, however have a reasonable understanding about how things work. I didn’t think it would be possible for anyone to delete the info from my database in this way without CPanel access (The rest of my site has not been affected). I would really like to get into using the functions of the blog, however am a little reluctant to re-enter the data again if this keeps happening. If anyone can offer any assistance, I’d be most grateful. Thanks in advance all the way from Australia. Angela