You should have received an email with more diagnostic information in it. The screenshot you submitted is pretty much useless for tracking down the problem. The email is what you need to find the reason for the problem.
Seems strange that you would have encountered a database problem arbitrarily. May I enquire, have you been making any alterations to your forum recently such as installing modifications, or editing files or templates?
go into config file and write ur email adresse in email place ...
go to database error page and then go to ur email you have recieve an email ... p
show us that so that we know what is wrong with ur database