Today try to access my drupal site on Fedora Core 6 server but,

the only page apper is error message that say!

" Unable to connect to database server "

Unable to connect to database server

If you still have to install Drupal, proceed to the installation page.

If you have already finished installed Drupal, this either means that the username and password information in your settings.php file is incorrect or that we can't connect to the MySQL database server. This could mean your hosting provider's database server is down.

The MySQL error was: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2).

Currently, the username is XXXXXXXXXX and the database server is localhost.

• Are you sure you have the correct username and password?
• Are you sure that you have typed the correct hostname?
• Are you sure that the database server is running?

For more help, see the Installation and upgrading handbook. If you are unsure what these terms mean you should probably contact your hosting provider.

Solution:

 Reason:The database server is down

 [root@tenouk ~]# service mysqld status
mysqld is stopped

Then try to start/restart you database server, in my case the database server is MySql 

[root@tenouk ~]# service mysqld start
Starting MySQL:                                            [  OK  ]
[root@tenouk ~]#

 Thenrefresh your web browser :-)