@Agalaro What you've described is typical when a save is corrupt: the loading process bounces and doesn't show the sims or most of the household data. If you can, try switching to a different household in Edit Town. That may or may not help, but at this point, there aren't a lot of options.
If you're willing to try a few mods, I'd suggest adding NRaas ErrorTrap, Overwatch, and MasterController. You can find descriptions here:
ET and OW clean up bad data on their own, with no need for player input. MC doesn't do anything at all unless you use it to issue a command, and in this case, the town reset is the command you'd want. The problem is that sometimes a save can be too corrupt for these mods to fix it. But if switching active households doesn't help, and you don't have another backup save, there aren't any good options left aside from hoping these mods can repair most of the damage.
If you can load the save with these mods in place, let the game clock run for a few sim-minutes, then click on City Hall or an in-game computer and select NRaas > MasterController > Town Options > Reset Everything. When it's done, which may take a few minutes, it'll let you know. Let the game clock run for a few more sim-minutes, then "save as" to rename the save (so the current backup remains intact should you need it later), quit, reload, and see whether the save is playable again.
While troubleshooting, be sure to delete the five cache files in your Sims 3 user folder, in Documents > Electronic Arts, every time you quit the game. These files should be deleted regularly anyway as well. For reference, they are:
I will try those mods if deleting the caches doesn’t work but since so many saves are becoming corrupt I think this particular sim is just cursed ☹️
