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