<span id="login" class="login">
        
        <?php 


        if(!isset($_POST['submit'])&&$_SESSION['user'] == "")  {  ?>
          <form class="form" name="log" id="log" method="post" action="<?php $PHP_SELF ?>">
          <label class="label">Login:   
          <input class="log" type="text" name="user" tabindex="1" <?php if($_POST['user'] != "" ) {echo ' value="'.$_POST['user'].'"';} else {echo ' value="Nutzername"';} ?>>
          </label>
          <label class="label"> 
          <input class="log" type="password" name="passwort" value="passwort" tabindex="2" />
          <input class="submit" src="img/submit.jpg" type="image" border="0" name="submit" value="submit" tabindex="3" />
          </label>
          </form>
        <?php
  }elseif($_SESSION['user']==""){

      .........

    if($password != $result['pass']){
      echo '<form action="index.php" method="post">';
      echo '<p align="center">Sorry, aber dieses Passwort ist falsch!';

        ........

    }else{

      <span class="padding_left smaller">Willkommen blabla

        ........
      
      <?php
    }
  } elseif($_SESSION['user']!="") {  ?>
    <span class="padding_left smaller">Willkommen blabla

        .......

    <?php }
  ?>