访问www目录外的php脚本

I have a my login details and connect file defined in a folder which is outside www/public. And it works ok. However, I have a got a form and when the user clicks on submit I would the request to be handled by a file in this folder again due to security reasons (which is outside the www folder). However, it tells me access forbidden as if there's an htaccess file (but there isn't such).

     <form action="/C:/xampp/login_mysql/process_login.php" method="post"   
     name="login_form">                      
        User: <input type="text" name="username" id="username"/>
        Password: <input type="password" 
                         name="password" 
                         id="password"/>
        <input type="submit" 
               value="Login" /> 
    </form>