Images missing in backend

I’ve been attempting to edit some of the content and images that I’ve got on a few different pages… but I’ve noticed the images suddenly disappear when I go to edit them. They show up just fine on the front end or where the general public sees the pages/content/images, but when I go to edit the page, half of the content is missing in the traditional Visual and Text layout area. So you can see the text, but all or in some cases a few of the images that are actually displaying on the page are gone. And yes, I’ve switched from the “text” tab to the “visual” tab… that doesn’t seem to be the issue… the images are still gone and I’m left with no way to edit them. What am I doing wrong? Is it possible to edit the title tag or alt title in my media library and have it apply to all the pages that image is attached? Or is there an alternative way to edit those images (say from the front end) that I haven’t yet learned to do?