This sounds like a common problem that Origin game players have been having since early Sept.
Log into Origin, and click on the My Games Tab, in this tab you should find all your installed Origin games. - Mouse over any of your games and click the little i for more details. This will show what content you have for said game and let you download any of it's content.
** EA recently changed how some expansions show up in the Origin Client (in Sept.2015). You can now find them in a different place, just right-click the respective game tile under "My Games" and choose "View Game Details".
Check out this thread here for a detailed visual guide:
http://answers.ea.com/t5/Origin/Missing-expansions-Be-sure-to-check-here/td-p/4438200====
If by chance your user files or install files have gone missing, you may need to first check to make sure you've installed the game correctly. If the game is installed correctly, navigate to the folders below to see if you can find your files. If they aren't there. You may need to search your computer for these folders.
User files should be located here:
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\Documents\Electronic Arts\The Sims 3
\Documents\Electronic Arts\The Sims 4
==
Game install files should be located here: (by default)
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C:\Programs(x86)\Electronic Arts for the DVD Version
C:\Programs(x86)\Origin Games for the Download Version through Origin
If your user files aren't in your \Documents\Electronic Arts\ (Sims 3 or 4) folder, move them from where you found them into one of those folders. As that is where the game save the user files by default.
MrsFlynn