Here's a few things you can do to see if you can save it...
1) Download the safe mode version of 1.3.0 and the bugfix pack and overwrite the sources, this will ensure that no hacker has altered code and 1.3.1 will ensure that all the known bugs are fixed.
2) Backup your board using my backup script:
http://www.yabb.info/community/index.php?board=1;action=display;threadid=7224, it contains instructions in the ZIP file.
If you want to know whether you run in safe mode create a file called phpinfo.php with this as the contents
<?phpphpinfo();?>
Upload it and call it through your browser and scroll down a until you find the part where it says
safe_mode, it the adjacent columns it will say whether it's on or off.
Safe mode is just a way for hosts to stop potentially bad actions carried out users (such as accessing another users webspace).
See if that helps
