delete user account PhP

hey guys im getting the account to delete only if i Put the correct user name and Password

but suppose the user enters a wrong user name and Password to delete an account
i want a message to disPlay saying wrong username or Password.
i tried this but im not getting it to echo the message "wrong username or password "if the user enter a wrong user name and Password

my code

<?php
include ('connect.php');

if (isset($_POST["submit"])){

      $user  = $_POST['u_name'];
      $pass  = $_POST['pwd'];
	  
if(!$user){
echo "please enter your username. <br>";
}
if(!$pass){
	echo "please enter your password";
	header('Refresh: 9; deleteform.php');
	}
if ($user && $pass){
	   $sql= ("DELETE FROM user_accounts WHERE username = '$user' AND password = '$pass' ");
	   $res = mysql_query($sql);
	   echo"your account has been deleted";
	   } ELSE {
		   echo"invalid username and password";
	  } 
		  
}
?>

PHP:

 

- Well, first of all, you need to sanitize your $_POST. See This. (for security purposes)

- You can check if that DELETE query was sucessfully by calling "mysql_affected_rows()" function.
If it returns 1, then the username and password were correct. Otherwise, invalid.

...
$res = mysql_query($sql);
     if (mysql_affected_rows() == 1)  echo "your account has been deleted";
      else echo "invalid username and password";

Code (markup):

- Also, you can put 'limit 1' at the end of the sql, i don't know how your database is structured, but that little change could increase speed.

 $sql= ("DELETE FROM user_accounts WHERE username = '$user' AND password = '$pass'  LIMIT 1");

Code (markup):

 

tnx worked perfectly