If you use an external hard drive, ensure the AC power cord and any subsequently connected power strip securely plugs into the power outlet and that both are switched on. Eliminate the port as the source of the problem by connecting your flash drive or external hard drive to another port. If the external storage isn’t recognized in another port, open Device Manger to determine if your port or drive has a system conflict. Select the Start button, Settings, and then click Control Panel. Double-click System, select the Hardware tab, and then click the Device Manager button. Click the plus sign (+) next to Universal Serial Bus Controllers for a drive that connects via USB and the plus sign next to IEEE 1394 Bus Host Controllers for a FireWire connected drive.
A yellow exclamation point signifies the port has a driver conflict, and a red “X” indicates the port has been disabled. Right-click and select Enable to reopen a disabled port. To resolve a port conflict, right-click and choose Uninstall for each controller until all the USB or IEEE 1394 Controllers are removed. After you uninstall each controller, restart your computer and it will reinstall the proper Bus Host Controllers. To check for an external storage conflict, select the Disk Drives heading and find your external storage drive. If the drive has a conflict, you may need to install its included software
and proprietary driver for the computer to recognize the device. If the drive still can’t be detected, uninstall the external drive and then reboot the computer to facilitate its detection.