pdoey on "Images not showing in backend media"

Hi,
Very inexperienced wordpress user here - can anyone please help?
I have recently just upgraded a site to latest 3.5.2 and have found that a lot of my images are not showing in back-end media although still showing in pages.
I have tried uploading some new pictures but these will not show and thus cannot get them into a post/page
http://www.cheapremovalsbury.co.uk