SEAC53I Please make sure you've placed the saves in the folder the game is currently reading, which may have changed without notice. Here's how to find it:
https://sims4.crinrict.com/eng/2018/07/how-to-find-your-user-folder/
If the saves still don't load, please post a screenshot of the contents of the folder that contains those saves, as in, I'd like to see the files' names and sizes. Include the address bar, above the list of files, in the screenshot.
If the Sims 4 folder is in a location you don't want to use, let me know where that is and what location you'd like the game to read.
Please also let me know what data is still missing. You've mentioned having at least some backup saves, but what about the rest?