The Sims 4 saves deleted from new computer

@Mochi_and_Jams  Saves are only stored locally, as in, on your computer, not on any EA\Origin servers.  However, if you ever used OneDrive, it may have synced your saves at some point.  You can sign into OneDrive on your computer or at onedrive.com.  If you find your saves, just move them back to Documents\Electronic Arts\The Sims 4\saves, and they should show up again.

If you do sign into OneDrive, I'd recommend disabling it again when you're done.  It mostly just gets in the way, and there are easier ways to back up critical data.

If your files aren't in OneDrive, and you never created another backup, then you're unfortunately out of luck.