"The Sims 4 is already running" Error message.

Hi, so this is my first time posting a topic on here, i'm new, so please excuse any vagueness or confusion.
So I just installed the new all in one, 'The Sims 4' and everything installed correctly, there were no issues with the installation. All of my 'redists' are installed & repaired, etc...
But I have two problems: 1 is that 'The Sims 4' file is not in my 'Documents/Electronic arts' folder. 2 is the main issue, whenever I try to launch the game, (TS4_x64) It does not launch & gives me an error with the following: "The sims 4 is already running" When it isn't running at all. I've tried to fix this for days non stop, uninstalling & reinstalling everything at least 4 times, restarting my computer, i've looked for solutions but i can't find anything.. I've had The Sims 4 before and everything worked fine, so it is completely compatible with my computer. Can someone please help me? I really have no clue what to do at this point, help would be very very greatly appreciated. Sorry for any inconvenience, thank you so much if you can help.

Since the all-in-one is in .iso format it could be that the settings for discs on your computer is set as "Run when inserted".
Try this:
Copy the contents of the all-in-one download to any location on your (external) hard disk.
Then eject the virtual disc (iso) by rightclicking on the virtual DVD station and select Eject.
Re-boot the computer

EDIT//

You stated that you have played The Sims 4 before, so there must have been a folder The Sims 4 in Documents\Electronic Arts unless you deleted it.

Tarac wrote:Since the all-in-one is in .iso format it could be that the settings for discs on your computer is set as "Run when inserted".
Try this:
Copy the contents of the all-in-one download to any location on your (external) hard disk.
Then eject the virtual disc (iso) by rightclicking on the virtual DVD station and select Eject.
Re-boot the computer

I'm sorry for inconveniencing you further more, but I don't think I have an External Hard Disk with enough space to hold the contents of my download... Also, to your edit/second reply: I have had the sims 4 before but I have deleted it, so there isn't still an existing file.
Again, sorry for any inconvenience, I really appreciate your help! But I still can't find a way to make this work because I don't have an External Hard disk... Any other ideas? Thank you for your help.

You don't need an external HDD, you can of course also copy the contents of the .iso to your C: drive

Tarac wrote:You don't need an external HDD, you can of course also copy the contents of the .iso to your C: drive

Thank you so much!! It actually worked!! Thank you, I've been trying to fix it for days and you helped so much! It was so simple, too. I wish I could repay you lol, thank you again!!

luyoowung wrote:

Tarac wrote:You don't need an external HDD, you can of course also copy the contents of the .iso to your C: drive

Thank you so much!! It actually worked!! Thank you, I've been trying to fix it for days and you helped so much! It was so simple, too. I wish I could repay you lol, thank you again!!

Don't forget to add the new location of the copied .iso to the exceptions of your anti-virus program.
Only in case that your AV already disabled OrangeEmu.dll,:  inside the folder Game\Bin you'll find a file OrangeEmu.rar. Extract with Winrar overwriting existing files.