Recently a webhost made a change to their hosting which showed up the following error on hosting :
Your PHP installation appears to be missing the MySQL extension which is required by WordPress.
Open .htaccess file
Remove the line : suPHP_ConfigPath /home/username/www/folder
Go to Cpanel
Change Theme to Paper)Lantern
Open : MultiPHP Manager
Change PHP to new if you want
Create new Php.ini via MultiPHP INI Editor in Cpanel Menu
Trackback from your site.