I am trying to submit details via email using php, it has worked before for some reason it is not working now, can someone please help me as i have looked through it so many times and could not find the problem, thank you

Code:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<body>

<form action="welcome.php" method="post">
Name: <input type="text" name="name" />
Number: <input type="text" name="number" />
Email: <input type="text" name="email" />
Message: <input type="text" name="message" />
<input type="submit" />
</form>

</body>
</html>
PHP Code:
<?php
if(isset($_POST['email'])) {

/* subject and email variables */

    
$email_to "someone@example.com";
    
$email_subject "Contact Form";
?>

<html>
<head><title> Test </title>
</head>
<body>
<?php 
    
function died($error) {
        
// your error code can go here
        
echo "We are very sorry, but there were error(s) found with the form your submitted. ";
        echo 
"These errors appear below.<br /><br />";
        echo 
$error."<br /><br />";
        echo 
"Please go back and fix these errors.<br /><br />";
        die();
    }
// validation expected data exists
    
if(!isset($_POST['name']) ||
        !isset(
$_POST['email']) )
        
died('We are sorry, but there appears to be a problem with the form you submitted.');        
    
    
/*  collect data variables */
    
    
$name $_POST['name']; // required
    
$number $_POST['number']; // not required
    
$email_from $_POST['email']; // required
    
$comments $_POST['comments']; // not required
    
    
$error_message "";
    
$email_exp "^[A-Z0-9._%-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$";
  if(!
eregi($email_exp,$email_from)) {
      
$error_message .= 'The Email address you entered does not appear to be valid.<br />';
  }
    
$string_exp "^[a-z .'-]+$";
  if(!
eregi($string_exp,$name)) {
      
$error_message .= 'The Name you entered does not appear to be valid.<br />';
  }
  if(
strlen($error_message) > 0) {
      
died($error_message);
  }
    
$email_message "Contact Form details below.\n\n"
    
    function 
clean_string($string) {
      
$bad = array("content-type","bcc:","to:","cc:","href");
      return 
str_replace($bad,"",$string);
    }
    
$email_message .= "Name: ".clean_string($name)."\n";
    
$email_message .= "Contact Number: ".clean_string($number)."\n";
    
$email_message .= "Email: ".clean_string($email)."\n";
    
$email_message .= "Comments: ".clean_string($comments)."\n";
    
// create email headers
$headers 'From: '.$email_from."\r\n".
'Reply-To: '.$email_from."\r\n" .
'X-Mailer: PHP/' phpversion();
$headers .= "Content-type: text/html\r\n";
@
mail($email_to$email_subject$email_message$headers);  
?>

<h2> Thank You </h2>

</body>
</html>

<?
}
?>