I am not entirely sure what you're asking, but it sounds like you wanted to try to reinstall Sims 3? Or maybe your install files are missing?
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 to see where the path takes you.
----> Click Start, and in the search bar the comes up Search for Sims 3.
Game install files should be located here: (by default)
Sims 3 - C:\Program Files (x86)\Origin Games\The Sims 3
User files should be located here:
C:\Users\<Username>\Documents\Electronic Arts\The Sims 3
Read more with the link below:
My Sims User Folder or Install Files are Missing?
https://www.carls-sims-4-guide.com/forum/index.php?topic=29315.msg431335#msg431335