@sundancrHave you any mods or CC?
If yes move the mods folder to the desktop.
Now, whether you have mods or don't you need to find your game folder. Look for it in Documents / Electronic Arts / The Sims4
Find localthumbcache.package file in this game folder and delete it, delete also all folders with the word "cache" in the name - important!
The game will recreate it but without saved errors.
Then go to the Origin/Library - right-click on TS4 - option "repair game"
You have to wait until Origin will fix all packs, not only the base game.
Turn on the game to create a new, empty mods folder and check if a game is working now after repair without mods and CC.
Check if there are new updated versions of the mods and CC you are using.
Then copy from desktop your mods and CC and paste it in the new mods folder. First, paste script mods one by one every time checking if the game is OK. Do the same with CC but if you have a lot of this, try the 50/50 method. ( divide your CC into smaller batches for example 50 pieces in one subfolder and check these subfolders one by one)
If it will not work -some files in the game folder can be damaged- then try doing a factory reset as described in this post:
http://answers.ea.com/t5/The-Sims-4/FAQ-Troubleshooting-Steps-amp-Known-Issues/m-p/3621199I don't work for EA