Check your page source and establish the links of the header and image. if you used wp_meta_data to save the code then it still has the link with sub-directory on it ie (example.com/sub-domain/header.jpg). If the first options(wp_meta_data ) is right You will need to update the image location to remove sub-domain to make the image show up.
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You need to change siteurl and home in wp_options table
Check your page source and establish the links of the header and image. if you used
wp_meta_datato save the code then it still has the link with sub-directory on it ie (example.com/sub-domain/header.jpg). If the first options(wp_meta_data ) is right You will need to update the image location to remove sub-domain to make the image show up.