Soy nuevo en php y traté de desarrollar un script de inicio de sesión, pero cuando introduzco valores no funciona. Ni siquiera puedo encontrar los errores porque cuando hago clic en enviar, solo se actualiza la página

Aqui esta mi codigo

<?php include "../utilities/config.php"; 

foreach($_GET as $key=>$value)
{
${$key} = trim($value);
}
$error = '';
if($checking_member_availability == 'yes'){
if(empty($user_name)){
    $error .= "Please enter user name.<br />";
}
if(empty($password)){
    $error .= "Please enter password.<br />";
}
if(empty($error)){
        $sql = "select * from `".SITE_TABLE_PREFIX."user` where     email='".$user_name."' and pwd='".$password."'";
        $resultUser  = mysql_query($sql) or die(mysql_error().$sql);
        if(mysql_num_rows($resultUser)>0){
        $rowUser  = mysql_fetch_array($resultUser);
        $error .= '';
        $_SESSION['email']=$user_name;
        }else{
        $error .= "Please check Email and Password.";
    }
}

if(empty($error)){

    echo "myaccount.php";
}
else{
    echo "<font color='#A01D49'>$error</font>";
}
}
?>

Por favor, ¿alguien puede ayudarme? He pasado mucho tiempo sin éxito.

Aquí está el código html

<script type="text/javascript" language="javascript">
function validation()
{
var password = trim(document.form1.password.value);
var user_name = trim(document.form1.user_name.value);
var type = trim(document.form1.type.value);
http.open("GET", "processor.php?checking_member_availability=yes&password="+
                    escape(password)+"&user_name="+   escape(user_name)+"&type=" + escape(type)  , true);
http.onreadystatechange = handleHttpResponse;
http.send(null);
return false;
}
</script>
</head>
<table width="241" border="0" cellspacing="0" cellpadding="0">
        <tr>
          <td><table width="100%" border="0" cellspacing="0" cellpadding="0" <?php   if($_SESSION['user_id']!=''){?> style="display:none;"<?php }?>>
              <tr>
                <td align="left" valign="top" class="loginBg">
                    <img src="img/logintxt.jpg" alt = '' width='100' height='29' border='0'>
                </td>
              </tr>
              <tr>
                <td align="left" valign="top" class="login"><form name="form1" id="form1" action="" method="post" onSubmit="return validation();">
                    <table width="100%" border="0" cellspacing="0" cellpadding="0">
                     <tr><td colspan="3"><span id="user"></span></td></tr>
                      <tr>
                        <td align="left" valign="middle" class="height"><label class="boldtxt">Email:</label></td>
                        <td align="left" valign="middle" class="heightMid"><input type="text" name="email" id="email" />
                        </td>
                      </tr>
                      <tr>
                        <td align="left" valign="middle"><label class="boldtxt">Password:</label></td>
                        <td align="left" valign="top"><table width="100%" border="0" cellspacing="0" cellpadding="0">
                            <tr>
                              <td align="left" valign="top"><input type="password" name="password" id='password' class="loginfld" />
                              </td>
                              <td align="left" valign="middle"><input type="image" src="img/submit.jpg" class="submit" onClick="return validation();" />
                              </td>
                            </tr>
                          </table></td>
                      </tr>
                      <tr>
                        <td align="left" valign="top">&nbsp;</td>
                        <td align="left" valign="top"><a href="forget_password.php" class="normalTxt">Forgot your password?</a><br />
                        </td>
                      </tr>
                    </table>
                  </form></td>
              </tr>
            </table></td>
        </tr>
        <tr>
          <td align="left" valign="top">
          <table width="100%" border="0" cellspacing="0" cellpadding="0">
                    <tr>
                      <td align="left" valign="top"><a href="provider_registration.php"><img src="images/applybut.jpg" alt="" border="0" class="apply" /></a></td>
                    </tr>
                    <tr>
                      <td align="left" valign="top">
                      <?=$value?>
                      </td>
                    </tr>
                    <tr>
                        <td align="left" valign="top">&nbsp;</td>
                    </tr>
                    <tr>
                      <td align="left" valign="top">&nbsp;</td>
                    </tr>
                </table>
          </td>
        </tr>
      </table>