Beatrice111111 If you're still looking for help, the error in your dxdiag points to an issue with .NET Framework 3.5, which Sims 3 uses. Click Windows key-R, enter appwiz.cpl without quotes in the run box, click "Turn Windows features on or off," and you'll see .NET 3.5 near the top of the list. Click the filled-in box to uninstall, and restart your computer. Repeat the process, clicking the now-empty box to reinstall, and restart again. If the box is already empty, click it and restart.
Separately, your computer's C partition is quite low on space, so it would be best to move some data to D, which is just another partition of the same drive. So you wouldn't lose any performance.
I would also suggest looking into upgrading the memory, which at 4 GB is going to be a limiting factor in much of what you do with this laptop.