Patio heater dissappeared

@boimah89  Is the item not available to buy, or not on a lot where you placed it?  If it's not in the Buy catalog, try repairing the game in Origin: open your game library, right-click on the Sims 4 icon, and select Repair.

If your sim's heater disappered from a lot, maybe another sim swiped it.  With the "sharing is caring" action plan, they'll steal anything not bolted down, and some stuff that is.