To figure out a solution to the problem by @un4saken
can you also let him know the steps you followed:
(a) how did you originally upload those images to your WordPress site?
(b) when you reinstalled the WordPress site - how did you reinstall it? Did you start a fresh installation and import the database? Did you import the images as well? As the database and images work separate from one another. In the days when I was still using this method I noticed my images were not uploaded with the database. You have to figure out where they are and then add the images to the images folder.
If I may offer a solution for future fault free option for migration of WordPress sites - I use the WP Plugin All-in-one WP migration tool.
. It's effortless to use. it's a plugin with which you download a full backup just with two clicks of your button from the plugin in your WP Dashboard to the hard disk of your computer. Then at the destination server you just install wordpress and add the plugin. Then upload the backup from the hard disk of your computer. Don't forget after the installation then to save the permalinks twice. Then everything appears exactly as it was when you made the backup including version of WordPress, images, etc.
I did some research with Google, since I've got a great interest in WordPress these seem to be possibilities for the images problem too.
1. If you uploaded the images through FileZilla the transfer mode of the images needs to be set to ASCII:
2. If you upload the WP database and images with the WordPress Importer you need to select "import images" option. Apparently some people forget to do that. The images were not imported automatically in the wp_posts database - you need to tell it to do so. They are stored in there as an "attachment" post type. The WP Gallery Shortcode references the id of each of those entries to build the gallery. Your media library also displays the images based upon the database. Wordpress doesn't just detect images in the uploads folder.
3. Also note that this could be theme related when Websites are moved or migrated. The issue can be caused by peculiarities of certain themes and doesn’t always occur. The only reason is to upload the needed files again and insert them anew.
4. If the above possibilities are not the case, it could also be the media folder path is set incorrectly - not sure why - but when I researched it that seems to be a possibility as well. You can fix it in the WP configuration file by setting it to wp-content/uploads.
5. Another possibility - when you upload your images through WordPress do you do it correctly through the media library? Like click on the media tool for uploading it, then clearly saving it in your media library. Like dragging and dropping or the easy ways aren't good apparently for when you want the images included when you migrate or reinstall the site.