In my gallery is happening the same thing, most thumbnails disapeared completly and some photos also. My version is Pro already and it was working perfectly until yesterday when there was a problem in the server. However i've been notifyied that everything is working ok now.
Please help. The link where this is happening is http://azuljasmim.info/Forum2009/index.php?action=gallery
And my version is Powered by SMF 1.1.10 with SMF Gallery Pro