Mysqli Extension

Dear List -

My mysqli extension seems to have gone away.

$host = 'localhost';
$user = 'root';
$password = 'SdR3908';
echo "hello2<br />";	
var_dump(function_exists('mysqli_connect'));// this returns boo(false)
$db = 'Store';
$cxn = mysqli_connect($host,$user,$password,$db);

I tried to reinstall -

rosenberg:/home/ethan#  apt-get install php5-common libapache2-mod-php5 
php5-cli
Reading package lists... Done
Building dependency tree
Reading state information... Done
libapache2-mod-php5 is already the newest version.
libapache2-mod-php5 set to manually installed.
php5-cli is already the newest version.
php5-cli set to manually installed.
php5-common is already the newest version.
php5-common set to manually installed.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

It did not help.

TIA

Ethan