You are asking how to bring people back, right? I didn't quite understand the second part of your question... sweatdrop
If your have Uni, you can bring a person back with the career reward for the paranormal career track. (I actually had a sim take the reward from the Secret Society house, but if you have night life, you can select the sim you want to have this object and type in the cheat box "unlock careerrewards.")
You have to pay the grim reaper around 8,800 simoleans for a full sim back. Anything less and you get a zombie, and too little you get a zombie with half their skills.
If you don't have Uni, then you'd probably have to use SimPE, but I don't know how.