It was against my better judgement, but I let my players have their lives back--after a LONG and HARD series of sessions.
We had an accidental TPK (flesh golem + already low hit points + no cleric + some idiot cast darkness = TPK). I described to each of the players what their afterlives were like, then I described them being ripped from the outer planes by a powerful summoning spell. Another party had used an artifact to bring them back 30 years after they had died. The mission the original party had been on was one to save the world from a green dragon who wished to become the avatar of the dark god Krarch. Since they died, the dragon succeeded and the world was plunged into decay, despair, and darkness.
After several sessions of despair, desperate odds, exhausting journeys, and 50,000 opportunities to die all over again, (sorry for how cheesy this is) I let them time travel back to only 2 months after they had died. They lost all of their equipment, but the campaign could go on.