My insert code stop working

[Max45]

I have created a simple mysql database with php code and I put it on server using on server phpmyadmin .
I added an insert button and everything was ok.But then the code stop working without no reason.
Here the URL of my database site: mathcalc.appleschat.com
Here the insertion code

<?php
 include "connectToDB.php";

 function mksafe($data){
     $data=trim($data);
     $data=strip_tags($data);
     $data=htmlspecialchars($data);
     $data=addslashes( $data);
     return $data

 }
   $value1 = mksafe($_POST['fname']);
   $value2 = mksafe($_POST['lname']);
   $value3 = mksafe($_POST['email']);
   $date = date('Y-m-d');
$sql = "INSERT INTO users (firstname, lastname, email,reg_date)
values( '$value1', '$value2', '$value3','$date')";

if ($conn->query($sql) === TRUE) {
    header("Refresh:0; url=index.php");
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}
$conn->close();
?>

Thanks in advance any help will be appreciated.

[benanamen]

OP was already advised about his code on another forum and did not implement any of the advice whatsoever. His response was "Could you please write it to me".

OP, we are not a coding on demand service. You apparently didn't even attempt to copy and paste the complete working example from the tutorial you were referred to. If you just want someone to write it for you then post a job offer on any of the forums jobs section.

Edited March 28, 2020 by benanamen