I can't play my game and I don't know how to fix it

Your problem should be have the title "The Sims4 is already running", @emma_mcdonnell7e.

Check if the games isn't running. Open the Taskmanager and check for "TS4_x64.exe" and "TS4.exe". Close any of them when found in the list.


Rename your "The Sims 4" folder in your "Documents\Electronic Arts\" folder
Clear the cache from Origin. How to do this, see here: https://help.ea.com/en-us/help/faq/clear-cache-to-fix-problems-with-your-games/
Repair The Sims through the Origin client, right click in your gamelibrary and choose the "Repair" option.


Start the Origin client and The Sims 4 as Administrator.

Disabling User Account Control (UAC)
https://support.microsoft.com/nl-nl/help/2526083/disabling-user-account-control-uac-on-windows-server

Make you're not running any other application that can prevent the Origin client and The Sims 4 from running. This means also any security software.
If this doesn't work, perform a clean boot of Windows: https://support.microsoft.com/en-us/help/929135/how-to-perform-a-clean-boot-in-windows

Create a new Administrator account in Windows 10, then login with that and try again.
https://support.microsoft.com/en-us/help/4026923/windows-10-create-a-local-user-or-administrator-account


Regards.