How can I get my sim back on sims 3?

Okay so my sim was a ghost hunter and a very high level one. She ended up having triplets, twins, and one other baby, three of which were ghosts. Then one day when she went to work and was trying to banish some ghosts she just disappeared. I have no idea what happened to her I just stopped being able to play her. For a little while her icon was still there but I couldn't click on it and then it disappeared too. On the loading screen when I click the family I want to play it still shows her even though she is dead and if I go to one of her babies relationships she is still there too. I don't know what to do though because all of her kids are babies and they can't do anything so I have to keep using cheats to keep them alive. I tried using cheats to add someone else to my household so I could still play but it won't work and I don't want to make the babies age until they are supposed to. I also can't go into edit town mode and add another person to the house because every time I click on edit town it says I can't go into edit town mode while one of my sims is dying. I think it says this because three of my sims are ghosts. I have tried everything and I don't know what to do, can anyone help?