Missing Sim PLEASE HELP EASY!?

few reasons why this could've happened..

you might have moved him out by mistake.

if the parents break up marriage, the one that got broken up with moves out.

living with some other family - another family you were playing could have proposed to 'move in' with them

or you went on moveobjects on and deleted him :p

try to ring him on the phone?

If Story Progression was on and you weren't playing their household, it's possible that they moved out. Check all the houses in the neighborhood for them. Unlikely, but they also might have died. Go to the Cemetery and click 'Manage the Dead' on the mausoleum and see if they show up there.

If you took him to the town and maybe forgot to bring him home, or he went to work and not came home it is possible there is a glitch in the system.

I can't remember how to fix it though.

Post your question on the Sims website in forums they will help you faster.

Do you have a brother or sister that may have a house somewhere in your sim world? Maybe while they were playing he died? Check their houses for a gravestone?

Sorry for your loss :(