Red X in media library

Hi,

Uploaded images and all appear fine throughout theme but are no longer available through media library – all I see is a red X, can’t add images to post from library either.

Site was built with a hosting provider I don’t usually deal with and I’ve never had this problem on other sites. In this instance they installed WP on secure server and switched it to live domain which is when the red X first appeared.

Should they have transferred all pages to the live domain, including the media library and would this resolve the problem?

Thanks, D