PHP发送电子邮件不起作用

i need help for my php contact form which is wrongly coded

HTML CODE:

<div id="contact_form" >
<form method="post" name="contact" action="contact.php">
<label for="author" style="font-size:14px;">Your Full Name:</label> 
<input type="text" id="author" name="name" class="input_field" />
<div class="clear h20"></div>
<label for="email" style="font-size:14px;">Your Phone Number/Email:</label
<input type="text" id="email" name="email" class="input_field" />

<div class="clear h20"></div>
<label for="text" style="font-size:14px;">Message:</label> 
<textarea id="text" name="comment" rows="0" cols="0" class="required"></textarea>
<div class="clear h20"></div>

<input style="font-size:16px;" type="submit" name="submit" value="Send"  />
</form>
</div> 

BELOW IS THE CODE THAT BEING LOADED FORM THE CONTACT.PHP TO THE HTML PHP CODE: (contact.php)

<?php
if(isset($_POST['submit'])) {
$to = "xxx@gmail.com";
$subject = "Contact Us";

// data the visitor provided
$name_field = filter_var($_POST['name'], FILTER_SANITIZE_STRING);
$email_field = filter_var($_POST['email'], FILTER_VALIDATE_EMAIL);
$comment = filter_var($_POST['comment'], FILTER_SANITIZE_STRING);

//constructing the message
$body = " From: $name_field

 E-Mail: $email_field

 Message:

    $comment";

// ...and away we go!
mail($to, $subject, $body);
?>

you just can not shut down the bracket! valid code is:

    <?php
if(isset($_POST['submit'])) {
    $to = "xxx@gmail.com";
    $subject = "Contact Us";

// data the visitor provided
    $name_field = filter_var($_POST['name'], FILTER_SANITIZE_STRING);
    $email_field = filter_var($_POST['email'], FILTER_VALIDATE_EMAIL);
    $comment = filter_var($_POST['comment'], FILTER_SANITIZE_STRING);

//constructing the message
    $body = " From: $name_field

 E-Mail: $email_field

 Message:

    $comment";

// ...and away we go!
    mail($to, $subject, $body);
}
?>

You forget to close your { at the end of your code.

<?php
if(isset($_POST['submit'])) {
$to = "xxx@gmail.com";
$subject = "Contact Us";

// data the visitor provided
$name_field = filter_var($_POST['name'], FILTER_SANITIZE_STRING);
$email_field = filter_var($_POST['email'], FILTER_VALIDATE_EMAIL);
$comment = filter_var($_POST['comment'], FILTER_SANITIZE_STRING);

//constructing the message
$body = " From:" .$name_field."

 E-Mail: ".$email_field."

     Message:

    ".$comment";

// ...and away we go!
mail($to, $subject, $body);
}
?>