index/redirect problem on localhost/mysql

[Charles Siegel]

Hi.. I am just learning mysql and php. I thought I had mysqli and pdo issues fixed but did something stupid I suppose. Trying to learn php connecting with mysql, I used this code:

<?php
$servername = "localhost";
$username = "zzzz";
$password = "zzzz";
$dbname = "zzzzz";

// Create connection
$conn = new mysqli($servername, $username, $password,$dbname);

if ($conn->connect_error)
{
die("Connection failed: " . $conn->connect_error);
}
// sql to delete a record
$sql = "DELETE FROM golfers WHERE lname = 'Adams'";

if ($conn->query($sql) === TRUE) {
header("Location: index.php");
} else {
echo "Error deleting record: " . $conn->error;
}

$conn->close();

copied and pasted in haste and didn't notice this line which I don't understand: header("Location: index.php");

Immediately after doing this the localhost/php_del.php url did not work at all. After rebooting the computer I found that none of my scripts that connect php to mysql work at all. I get this message now: Fatal error: Uncaught Error: Class 'mysqli' not found in C:\Apache24\htdocs\php_del.php:8 Stack trace: #0 {main} thrown in C:\Apache24\htdocs\php_del.php on line 8. I believe I have screwed up some index or caused a redirection problem.

I have no idea how to fix this. Can anyone help?

Thanks much!