Remotely assisted PASI in checking the issue of NAV 2009, they checked the database and application servers and found an error from the event viewer. They tried to connect to the live database with SQL and were able to access it, however, I advised that this is not the application that the end users are accessing. They requested to remotely access an end user, after checking, they found that the instances stopped running. They restarted the instances of the database that encountered the error, after that, the application are now able to access.