My phpbb forum 360-forum.net has all of a sudden started giving the error thats on there right now. Im sorry but i can only offer the points i have right now but it will be greatly appreciated!
Did you make any changes to the config.php?
Some other things to check for in cpanel,
Make sure db exists, dbuser exists, dbuser assigned to db. And then pull up phpmyadmin and see if the db is populated. Well there would be different errors if it wasnt populated. Anyhow, check for the above.
Can you remember the very last thing you did to your hosting account/server or even editing the phpbb files? Or did this just happen on its own? No sarcasm givin - It does happen
Kindly, Do you have backups?
--edit--
do you have shell access? You can always try to connect to db with command line to test it.
be back shortly, din din time.