@BellaB183 This isn't a problem for Sims 4: the game will know what to do with the .package files regardless of the association Windows has set. You can simply ignore the Notepad icon.
If your most or custom content aren't working, trash the current ones and download new copies. They'll show the same association, but the new files should be fine.
Sims 4 won't even open. My computer turned all of the package files with sims 4 into notepad files and now won't open
No, your computer did not turn package files into notepad files. You or someone else using the computer tried to open a package file with notepad while having "Always open with" checked thus causing it to be associated with notepad. This does however not change how it works.
You say that Sims 4 do not start. Please rightclick the Game in Origin and select "Repair". If it doesn't work after having done that post what happens when you try to start the game.
It tries to open but the screen goes black like it's loading then it minimizes itself and refuses to open.
Please post a DxDiag. https://help.ea.com/en-us/help/pc/how-to-gather-dxdiag-information/
You can attach the txt file directly to your answer.
