Death

You can resurrect a ghost-Sim back to life (so if you still have the tombstone), but it will take a little bit of effort. You must bake ambrosia. Because this metod is a bit complicated, I will explain it in steps:

step 1: max both the cooking & gourmet cooking skill and improve the gardening skill to lvl 5 (works with and without cheats). This is necessary, because you will need a deathflower, an angelfish and a potion of youth.

step 2: buy the potion of youth from the reward store in exchange for 1500 satisfaction points. You can receive satisfaction points by working on your aspiration.

step 3: fish in Willow Creek to catck the angelfish. It's an uncommon fish, so it will probably take a few catches. (though fishing is always based on luck)

Step 4: At lvl 5 of gardening it's possible for your sim to start grafting(it's like mixing plants together in order to create new species of plants). You will need this grafting to obtain a deathflower. Graft like this:

Graft apple with cherry to create pommegranate. Graft lilly with snapdragon to create orchid. So plant these seeds into trees and harvest them. You can graft this with the others to make a deathflower seed. Plant the tree and harvest its deathflowers. (btw: you can also give these flowers to the grim reaper when your sim is dying to prevent its death).

Step 5: when you gathered this 3 ingredients, cook a gourmet meal via the fridge.You will make a perfect plate of ambrosia. 

Step 6: Before you give the plate to the ghost to the sim you wanna revive, you must invite him to your household. Befriend the sim to invite it to your household via social interactions and once you did that and your sim's ghost is added to your household, you can make him eat the ambrosia and it will revive back to life!!

Did you know that ghosts have various unique traits which are also fun to explore and there are also ways to prevent their death on beforehand. Such as giving the deathflower to the Grim Reaper or with a book of life and many more. (I use the book of life method a lot, it works like this: choose the best selling author life goal for your sim. Incrase the writing skill to level 10 and complete the aspiration and when you did the both of them you can find a new interaction on your computer called ''The book of life'' in the writing section. Write the book(it will take a few simhours). So when you wrote this book, you can choose the ''Capture epic saga'' interaction. Here you can choose the sim you want to save from death, so when it dies you can summon the sim with the book. Befriend the sim to invite it to your household via social interactiosn and once you did that, you can revert it back to life with the ''restore life'' interaction. The book will disappear afterwards. Also, when alive, the targeted sim can read this book aswell in order to fullfill it's needs easily.)