header, stylesheet not being read

It sounds like your theme template file(s) are not using get_header, which is the function that loads your header.php. If so, you will need to add get_header(); to the top of each of your template files.

My guess is that your theme template files are missing get_footer also as nothing that would normally be in that file, such as </body> or </html>, is printing either.

error code: 523