@Jeand1963 Are you playing through Origin or the EA App? If the latter, I'd suggest going back to Origin, at least for now. The EA App has some trouble with store content, and although that should be fixed sooner or later, you probably don't want to wait. You can find a download link for Origin here:
https://answers.ea.com/t5/Origin-Client-Web-Technical/Downloading-and-installing-Origin-Windows-and-Mac/m-p/11915666
If you get an error when opening Origin, restart your computer, or open the Task Manager and kill the EABackgroundService.exe.
If the EA App isn't the problem, please move the entire Sims 3 folder out of Documents > Electronic Arts and onto your desktop. Open the launcher to spawn a clean folder, download one world and install it, and see whether it shows up in-game. If it does, you can install the rest of your store content, but do so in small batches, and install each world as a separate step—the launcher doesn't handle large amounts of data very well.
Once your store content is reinstalled, that is if this works, you can move your saves and anything else you want to keep from the old Sims 3 folder to the new one. Saves are in the Saves folder, saved households and builds in Library, sims saved in CAS in SavedSims, etc. It's best to leave new copies of files or folders in place and only copy over the content that doesn't get recreated, like your saves.