147682102I The easiest way to fix this is to revert to an older copy of your save. Here's how:
https://sims4.crinrict.com/eng/2014/09/recover-backup-save-game/
If none of the backup saves have your other sims, don't save your progress, just let me know. And in that case, please also check that your packs are all still loading in-game. The simplest way to do that is to enter CAS or Build/Buy and try to filter by pack. Any DLC you don't have installed or that isn't loaded will be listed as not owned, even the ones you do own.