I don't know how to put back save files

Rendellm​  The saves go where you found them: in Documents > Electronic Arts > The Sims 4 > saves.  You can simply drag and drop the files.

If the saves aren't showing in-game, make sure they're in the folder Sims 4 is actually reading.  Here's how to find it:

https://sims4.crinrict.com/eng/2018/07/how-to-find-your-user-folder/