Says that the game is running but it isn't

I haven’t been able to play for months because whenever I try to open the game, I get the error shown in the screenshot, even though it’s not true that the game is running. In fact, when I press OK everything closes and it sends me back to the EA menu.

I thought the problem might have been because my game was installed on an external hard drive, so I tried uninstalling and reinstalling both on my desktop and on the external drive (and I followed the correct procedure). Nothing worked.

I also tried both without and with mods (only custom content, no gameplay mods), but that didn’t make any difference either. A while back I managed to open the game for the first time, but it wouldn’t let me enter a lot and only took me to CAS, and then it started showing issues, like the screen not fitting my computer display. The game then crashed. What can I do?