WordPress Database error and repair

Error connecting to your database is common, but it isn’t necessarily a problem with wordpress itself.
– double check your wp-config.php file settings for the database name, database username and database password. This is where most errors occur.
– Then check that you don’t need to change the database host from “localhost” to something else. You can get that info from your hosting provider.
– Check you have actually created a database with the same database name as is in your wp-config.php file.
– Last, but not least, if all that information is correct your database probably has a problem with it, and you may need to contact your hosting provider if the database server is online / if they have any other problem at their end, or they made any changes to your account, or if there are any limitations/restrictions, if the hosting package is set to Windows and not Linux, etc.
– There are also many threads on this topic on these forums: http://wordpress.org/search/Error+establishing+a+database+connection?forums=1

Try reviewing:

http://codex.wordpress.org/FAQ_Troubleshooting#How_do_you_repair_a_MySQL_database_table.3F

Once you have repaired the database, if the issue still persists, Try:

-deactivating ALL plugins temporarily to see if this resolves the problem. If this works, re-activate them individually (one-by-one) to find the problematic plugin(s). If you can’t get into your admin dashboard, try deactivating via FTP or SFTP or whatever file management application your host provides. If applicible, also remember to deactivate any plugins in the mu-plugins folder. The easiest way is to rename that folder to mu-plugins-old.
– To rule out any theme-specific issue, try switching to the unedited default theme for a moment using the WP dashboard. If you don’t have access to your admin area, you can switch to the default theme by renaming your current theme’s folder in wp-content/themes and adding “-old” to the end of the folder name using via FTP or SFTP or whatever file management application your host provides. Alternately, you can remove other themes except the default theme. That will force your site to use it.
– resetting the plugins folder by FTP or PhpMyAdmin. Sometimes, an apparently inactive plugin can still cause problems (because the hooks remain unless plugins completely removed or some plugins stick around in cached files. So by renaming the folder, you break them and force them inactive).