rinniex00 Please uninstall and reinstall .NET Framework 3.5, which Sims 3 uses. Click Windows key-R, enter appwiz.cpl in the run box, select "Turn Windows features on or off," and .NET 3.5 should be near the top of the list. Click the filled-in box next to it to uninstall, and restart your computer. Repeat the process, clicking the now-empty box to reinstall, and restart again.
If .NET Framework 3.5 is not already installed, you can simply install it and restart.
If you get an error when trying to uninstall or reinstall it, please post a screenshot. I can plug it into Google Translate for images if necessary.
