I have images that I uploaded to the media library and which are in use on the website but when I go to the media library they are missing - different ones at different times. The display of images seems limited to a certain amount and then no further pictures are visible. So, for instance, I may have a group of images that I want to edit and add to. I go to the media folder and find ones that I want to add are not visible - even though they might be present on another page and I know 100% that I successfully uploaded them. Any answers much appreciated as this wastes an awful lot of time.
This should usually be a comment but I don't have enough reputation yet to comment. Your question is a little confusing which is why I am having problems trying to answer it.
Are you talking about the WordPress media library or folder? One of them you can reach from inside the dashboard (under Media), the other is the physical folder on your server (reachable via FTP). You use both in your question so it would be great to understand which one is the problem.
Where on your site does the display of images seem limited? On what other page are the images visible?
If you could elaborate on those points (maybe give a step-by-step explanation of what you are doing), maybe I or someone else here would be able to help you.