Warning: PDOStatement::execute():

J'essaye de contruire un code mot de passe oublié, j'ai des erreurs

1)Warning: PDOStatement::execute(): SQLSTATE[HY093]: Invalid parameter number: parameter was not defined in C:\wamp\www\ndameyong\Classes\Db.php on line 68
2) Fatal error: Uncaught Error: Call to a member function rowCount() on int in C:\wamp\www\ndameyong\forgot.php on line 31
( ! ) Error: Call to a member function rowCount() on int in C:\wamp\www\ndameyong\forgot.php on line 31
voilà mon code forgot.php

<?php require 'includes/includes.php';
if(!empty($_SESSION['user'])){
  header('location:profil.php');
} 
?>
<?php 
$titrepage="Mot de passe oublié || Ndameyong - L'Ecole des Langues Camerounaises" ;
require 'includes/header.php'; 
?>

<?php
$title = 'Mot de passe oublié';

if(!empty($_POST))
{
    $post = filter_input_array(INPUT_POST, FILTER_SANITIZE_STRING);
    extract($post);

    $errors = [];


    if(empty($email) || !filter_var($email, FILTER_VALIDATE_EMAIL)){
      array_push($errors, 'Cette email est invalide.');
    }
    else{
      $sql = "SELECT * FROM users WHERE email=:email";
     $data = [':email']; 
$req = $DB->exec($sql , $data) ;


      if(!$req->rowCount()){
        array_push($errors, 'Cet email ne correspond à aucun membre du site.');
      }
      else{
        $user = $req->fetch();
      }

      if(empty($errors))
      {
        $token = uniqid();

        $req = $db->prepare('INSERT INTO password_resets (email, token, created_at) VALUES (:email, :token, NOW())');


        $sql = 'DELETE FROM users WHERE id=:id';
        $data = [':id'=>$user['id']]; 
        $del = $DB->exec($sql , $data) ;

        $req->bindValue(':email', $email, PDO::PARAM_STR);
        $req->bindValue(':token', $token, PDO::PARAM_STR);
        $req->execute();

        $link = 'Bonjour, veuillez cliquer sur <a href="https://membres.test/reset.php?token='.$token.'">ce lien</a> pour réinitialiser votre mote de passe.';

        // Create the Transport
        $transport = (new Swift_SmtpTransport('smtp.mailtrap.io', 465))
          ->setUsername('fae489573327ac')
          ->setPassword('eed3d4ab64b373')
        ;

        // Create the Mailer using your created Transport
        $mailer = new Swift_Mailer($transport);

        // Create a message
        $message = (new Swift_Message('Mot de passe oublié'))
          ->setFrom(['lcorrefabien@gmail.com' => 'John Doe'])
          ->setTo([$email => $user->name])
          ->addPart($link, 'text/html');
          ;

        // Send the message
        $result = $mailer->send($message);

        if($result){
          $success = 'Un email vous a été envoyé avec des instructions.';
          unset($email);
        }
      }
    }
}

?>
    <h2>Récupérez votre mot de passe</h2>

    <?php include('messages.php');?>

    <form action="forgot.php" method="post">
      <div class="form-group">
        <label for="email">Email</label>
        <input type="email" name="email" class="form-control" placeholder="Email" value="<?= $email ?? '';?>">
      </div>
      <button type="submit" class="btn btn-primary">Envoyer</button>
    </form>
    <br>

    <p><a href="login.php">Je m'en souviens en fait.</a></p>

<?php require 'includes/footer2.php'; ?>

Db.php

<?php
 
/**

 Gestion de la base de données*/class Db{         private $host=HOST;    private $name=DBNAME;    private $user=USER;    private $pass=PWD;     private $connexion;     function __construct($host=null,$name=null,$user=null,$pass=null){                 if($host != null){            $this->host = $host;            $this->name = $name;            $this->user = $user;            $this->pass = $pass;        }         try{             $this->connexion = new PDO('mysql:host='.$this->host.';dbname='.$this->name,                $this->user,$this->pass,array(                    1002 =>'SET NAMES UTF8',                    PDO::ATTR_ERRMODE => PDO::ERRMODE_WARNING                    ));            $this->connexion->exec('SET NAMES utf8');//PDO::MYSQL_ATTR_INIT_COMMAND        }catch (PDOException $e){            //echo 'Erreur : Impossible de se connecter  à la BD !';die();            echo $e->getMessage();        }     }    /* requete */     public function query($sql , $data=array()){        $req = $this->connexion->prepare($sql);        $req->execute($data);        return $req->fetchAll(PDO::FETCH_OBJ);    }     public function tquery($sql , $data=array()){        $req = $this->connexion->prepare($sql);        $req->execute($data);        return $req->fetchAll(PDO::FETCH_ASSOC);    }      public function insert($sql , $data=array()){        $req = $this->connexion->prepare($sql);        $nb=$req->execute($data);        return $nb;    }    		public function exec($sql , $data=array()){      try{        $req = $this->connexion->prepare($sql);        $req->execute($data);        return $req->rowCount(); // Retourne le nombre de lignes impactées par la reuqête      }catch(Exception $e){        echo 'Erreur : ' . $e->getMessage(); // en cas d'erreur dans la requête !      }    }    public function deleteuser($id){       $sql = 'DELETE FROM users WHERE id=:id';       $data = [':id'=>$id];        return  $DB->exec($sql , $data) ;    }  public function uniqueEmail($email){        $req = $this->connexion->prepare('SELECT count(*) as nbre from users WHERE email=:email limit 1');        $req->execute(array('email'=>$email));         $reponse = $req->fetchAll(PDO::FETCH_ASSOC);        return $reponse[0]['nbre'];     }}

merci d'avance