Php – Fatal error: Class ‘PDO’ not found ( but it is installed and works on the terminal )

I got into a very odd situation.

My website hosted on a shared hosting, from out of the blue, stopped working reporting Fatal error: Class 'PDO' not found

So I created a verification file called test.php and placed it in the public_html folder.

test.php:

<?php
if (class_exists('PDO')) {
  print "PDO is installed"; 
}
else {
  print "PDO NOT installed";
}

phpinfo();
?>

So the above script checks if the PDO class is present and right after that prints php info about what is installed and enabled.

So first I did some tests on the SSH Terminal:

• Before running the test.php I checked for the installed modules: $ php -m and both PDO and PDO_mysql were there;
• Then I ran $ cd public_html $ php -f test.php. It returned that the PDO class was installed and both PDO and PDO_mysql were listed from the phpinfo() call.

Then I ran the test.php on the web browser. It returned PDO NOT installed and either PDO and PDO_mysql were listed in the phpinfo() print call.

What could possibly cause such a behaviour?

UPDATE:

I have already tried to add the extension lines below into the php.ini but
the issue persisted. I also made sure I had added those line into the
right php.ini file by calling get_cfg_var('cfg_file_path')

extension=pdo.so

extension=pdo_mysql.so