Occasionally I come across systems that will no longer detect USB devices when they are plugged in, no matter which port they are connected to.
If this happens to you then the first step should always be to shut down your system completely and remove power. This will free up any of the USB hardware that nay be ‘hung’ resulting in them appearing non-responsive.
If, after a complete cold re-start, the USB ports are still not detecting any devices connected you should check out the ‘Selective Suspend’ settings on your system.
This feature is usually enabled by default on systems as it can conserve energy and extend battery life. However, in some circumstances this process can also cause the USB ports to get locked up. In this case you should turn off the ‘selective suspend’ feature. To do this…
Open your Control Panel and Select Power Options
Click on Change Plan Settings for the plan that you have selected
Click on Advanced Power Settings
Expand the USB section
Click on the drop down
Reboot your PC.
If the ‘selective suspend’ was the culprit then you should now be able to access your USB port.
Hope this helps someone out.