ComputerBB

I am not good with computers at all, so im not even sure if this question is even in the right section. Im sorry if it is not...Okay well anyways here is my problem, I am trying to go to a website, but everytime i go to it this pops up on the screen "MySQL has encountered an unknown error. To find out the exact problem, please set the DEBUG flag to true in header.php." i know that the website works because i was just their the other day and it just started doing this a few days ago. I would greatly apperciate it if someone could help me out with problem....Thank you...