Re: "Sims 4 is already running"
Sometimes that can happen when your computer still has the game registered as running in the task manager. hold down CTRL + ALT + DELETE and select the task manager option to open the task manager. If you see Sims4 listed as a program running, you can open up a click tab with a right click and select to manually shut it down with "End Task". Sometimes programs do not fully shut down all the way and this is a good way to check to see what is running in the background or to fix this issue. You should go ahead and restart your computer anyways. Hope this helps.