To fix the Windows Security Service can’t be started error on Windows PC, you need to go to the all running services. You can open that using the task manager, and then you have to find the Windows security service from there. And then open its properties where you need to set the startup type to Automatic (Delayed). And you would also need to click on the Start button to start the service. And then you have to restart the system to see if it is working or not.