Restore default header.php template on WP Twenty Ten

I just setup a site using wordpress, with twenty ten theme. I made the mistake of not creating a child theme, and I jacked my code up. I want to get back to default template code for header.php. I’m not talking about header image, but the actual original header.php code for twenty ten.

Googling the issue to no end, but can’t find default php code for that template!

Please Help!