images suddenly are missing on random posts and pages

Our wordpress website has been working great all images loading and working properly. Yesterday we began to notice that randomly on certain pages and posts, some photos are missing with only alt-text showing and they are not even in the media library any more. I fixed a couple by uploading them again from my computer but does anyone know the reason they would just disappear like that. I called godaddy and they said they’re not even showing on the server and they don’t know what happened.
http://www.stillwatersministries.net
Thanks,
Ann