Can't find ghost

is it your sim that died and the urn/tombstone is on your lot ?

it can take 1-3 sim days for the ghost to appear in your house then you should have the options to click on the ghost and ask about death etc

my sims ghost was showing up every other day  but he stopped showing   i clicked on the sim radio as i did have it set to spooky music BUT one of my  other sims must have changed the radio station to something else i turned it back to spooky music the ghost a few hours later is now showing up dunno if it'll work for you but try that see if the ghost will appear

 to add the ghost to my household as a  playable ghost just kept up the interactions to get to best friends then the option to invite to household pops u