The images are not gone. This is an error being reported by WordPress. This can happen if you moved web hosts and the new host does not have a properly configured image editor installed. Or, if you have not moved hosts, the web host has upgraded their server but did not properly install or configure an image editor.
WordPress will still allow you to upload images to its library but it is also unable to crop and optimize the images potentially slowing down your site as the full-size images are being served to your site’s visitors. CSS is then being used to scaled down the images.
Navigate to the Connections : Tools admin page and click the System Info tab. Scroll the info down until you come to the GD Support section. The GD PHP image library is the image library required by WP which is almost universally installed and configured by web hosts. If the system info says it is not installed, you’ll have to contact your web host and request that they install and configure it.
Hope this helps, let me know.