@Ryooner94 If you want the original furnishings for the apartment, you can always load a new game, go to that apartment in build mode. You must delete the doorway walls to make the whole apartment one room, then save it to your library (gallery? I am uncertain what it is called on PC for your personal builds).
Once you have saved the lot as a single room, go back to your original save and place the lot from your library(gallery) into place.
Replace the doorway walls and doors. Your apartment should be back to default in your original game, and you can move your sims in to a furnished apartment.
