How do I bring a sim back to life???

If you have University, you can use the Ressurect-O-Nomitron to call the Grim Reaper and bring them back.

It's a career reward in the Paranormal job. I've never tried it, but I have one just in case.

If you have the universidade game, you will have the Paranormal Phone of Resurrection. You can unlock this por using the boolprop testingcheatsenabled true code. Then you will control shift c and then in the box type: unlockallcareerrewards. I'm pretty sure that is how you do it. Then the phone will be unlocked and so will other really cool objects. If it says error type exit. Then check one of the websites with Sims 2 cheats.
Hope that helps! :)

If you don't have other sims on the lot you just don't save your game, if you do, use the expansion pack, University, that comes with the phone in the aspiration rewards, or you can use another sim to beg the grim reaper, where you might have a chance, and he might want money from you in which case you use the cheat: motherlode .

Well,i don't actually know if this is gonna work but try, click ctrl+shift+c and write in boolprop TestingCheatsenabled true,then shift+click on a sim. Click Spawn and then Tombstone of life and dead. There will be a grave near your sim. Click add sim to the family or something like that. If it comes alot of names then click on a sim's head and try another one that is similar. Click the name of the sim,and he or she will show up. If it dies then didn't work. Sorry if it don't work..

well i havent played in a while(because we just moved and i amtrying to find the game) but i think if you get the Tombstone of life and death there is this option that you can add someone to the family and most of the time if you go through the list you can find the name of the deceased and have them back.
i really dont remember all to well so i dont remember if it works
sorry if this isnt any of use to you