Is there anyway to bring back a Sim that was released to the Netherworld?

@vQrowv I don't believe so. It's my understanding that when the sim is released to the netherworld they are gone from the game. You could, however, roll back to a save from before they were released to the netherworld and consider options at that point. Do you have the option in-game to restore to an earlier save? If not, do you have any old backups you would like to restore to?

• Information on how to restore saves and how to restore to a backup save: https://sims4.crinrict.com/eng/2014/09/save-games/
• Information about death & ways to bring a ghost back to life:  https://www.carls-sims-4-guide.com/death/

SheriGR ☕ – I don’t work for EA

@vQrowv  In addition to what @SheriGR said, if the sim was created in CAS, you should have been prompted to save him/her to your library when you went to place the sim in game.  While you lose all the character data, you can add the sim back into the game with no skills, no aspirations, no purchase traits etc. so all you get is their appearance, initial traits and name.

If the sim was a Maxis premade, you can start a new game and go to manage households and save the sim to your library.  Or if the sim was a downloaded sim, it should still be in your library.

If the sim was an npc you moved in or a born ingame sim, then you're pretty much out of luck.

The only save file that is the most recent is from 2017. If I go back to that one, will it delete the current stuff I have now?

@vQrowv  There is a way to keep all your progress since the 2017 and get your sim back.  I'm sorry I didn't think of it earlier.   And it's pretty easy but it might take a few steps just so you don't mess up either save.  But the sim won't be quite the same as before she died.  And depending on how you do this, the entire household may not be the same.  But at least you can keep all your progress in the rest of your game the same as it currently is.

First thing, make a copy of your saves folder for both the old game and the new one and put them somewhere safe just in case.  Depending on how you create your games it may just be one folder.  

Then just open the old save and go to manage households and find the household with the sim you want back in it.  Open that household in CAS and save the household to your library.  Then exit the game without saving.

Now the next step depend on how you create your games.

If you just created your new game in the same Sims 4 folder where the older one is by just clicking on the new game button, then all you have to do is open the new save where she died, go to your library, find the household you just saved and put them on a lot somewhere.  Save and go to manage worlds, then open manage households and delete all the other sims in the household so only the one you want to save is left.  Then exit CAS.  Go back to manage households and merge her back into her family.  Then go to any of the map screens and open the command line window (CTRL-Shift-C) and type CAS.fulleditmode and then hit the enter key and close the command window.  Then edit the merged household in CAS.  Using that cheat will allow you to manually reset her relationships with the rest of the family to what they were at the time of her death just like you do when you create a new household so all you should have lost is the increases in skills, aspirations, etc. from 2017 to when she died.  

Now if you created your new game by renaming your the 2017 save Sims 4 folder to something else and created the new game by letting the game create a new Sims 4, then there is an extra step you have to do.  In windows explorer, open two windows.  One for the old Sims 4 folder and one for the new Sims 4 folder.  Drag and drop the Tray folder (that's your library) from the old one to the new one using copy.  Do not use move.   When the window pops up and asks if you want to replace any files say no.  That way, you don't overwrite something that you may have saved like a lot or other sims that you might have changed.  The only things that should copy over is any files the old library had that your new library doesn't including the household you just saved to your library from your old save.  Now that sim will be in your current game library and just open your game and the follow the directions as I described above.

If you have any questions about what I have said here or don't understand something, don't hesitate to ask.  I'm here several times a week so I will get back to you as soon as I see you've posted.   Hope this helps you.

Edit:  I just realized something.  I made an assumption that you are playing on a PC.  If you are that's great and this should work.  If you're playing on a PS4, XB1 or a Mac, I don't know if will or not.  Sorry.