Re: Sims 4 with my save data won't open

@41111037  Don't move the entire old Sims 4 folder back to its original location, and if you've done so already, please move it back to the desktop.  The point is to move the save files themselves from the old Sims 4 folder to the new one, leaving the rest of the content behind.

If you move only the saves files, nothing else, and the game won't launch, try removing all but one of the saves.  Be sure to leave a file that ends in .save, not .save.verx: those are the backups and won't be loaded.