Welcome welcome!
First of all, you can only revive people with grey portraits. If their portraits have disappear, they are dead forever.
To revive, you must go to a temple (there is one in most city-parts). Say you want to see their services, click on the dead persons portrait and buy "Revive".
You can also buy a revive-scroll in various stores, or use the priest/druid-spell revive, or Harpers Call.
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We call him Bobby Corwen