Unable to INSERT a row in a table with PDO - php

Question

I want to insert some data into a table using PDO. I looked for some examples and I found that I need to use the functions prepare, bind and then execute, however I can not figure out in my code what I am doing wrong because it inserted nothing and I have no error in the query or php code.
if($_POST){
$account = $_POST['account'];
$password = $_POST['password'];
$phone = $_POST['phone'];
$email = $_POST['email'];
$stmt = 'INSERT INTO employer(account, password, phone, email) VALUES(:account, :password, :phone, :email)';
$stmt = $conn->prepare($stmt);
$stmt->bindParam(':account', $account, PDO::PARAM_STR,100);
$stmt->bindParam(':password',$password, PDO::PARAM_STR,100);
$stmt->bindParam(':phone', $phone, PDO::PARAM_STR,100);
$stmt->bindParam(':email', $email, PDO::PARAM_STR,100);
if ($stmt->execute(array('account' => $account,
'password' => $password,
'phone' => $phone,
'email' =>$email
)
)
){
echo "success";
}else{
echo "error";
}
}

Answer 1

Error detected by #jeroen I was binding twice. So I can bind "either bind before the execute statement or send an array as a parameter, not both"
$stmt = $pdo->prepare('
INSERT INTO employer
(account, password, phone, mail)
values (:account, :password, :phone, :mail)');
$stmt->execute(
array(':account' => $account,
':password' => md5($password),
':phone' => $phone,
':mail' => $email
)
);
if ($pdo->lastInsertId())
return true;
else
return false;