How to detect USB Port status connected with a USB Flash drive? (working or idle). It seems no APIs or interfaces to get the status of a USB Port (working or idle). As workarounds, it may work to force reflush cache by unmounting and re-mounting volume or remove and rescan usb key device. 1. Flush disk cache by unmounting and re-mounting volume 2. Devcon remove "USB\VID_XXXX&PID_XXXX" and then "devcon rescan"