If you have the university expansion then you can bring them back from the dead using the ressurect-o-nomitron, its one of the career rewards.
I tried pleading to the grim reaper for my sims life, fell on deaf ears though, that Grim doesn't mess around lol
Your sim need to go to college, finish it, get a job in the paranormal career track, get to the top of it, use the career reward, the Resurrect O' Notion, when ol' Grimmy comes, pay him, like, the most amount of money if you want the real sim back. But I don't think however they will still have their memories. If you pay little, your sim that you wanted to resurrect, will be a zombie. Now i'm not saying pay the absolute least, (0-987) because Grimmy will get mad and take your money and leave, Ok: i stole this from another post, it might help. 988 - 4127: Zombie, resurrected sim gets angry with caller 4128 - 8512: Personality reversal 8513 - 10000: Perfect resurrection, resurrected sim gets relationship boost with caller And, yes, you need Uni.
