If your device is not being recognized or you are experiencing a different issue, reconnecting your KeepKey is the first troubleshooting step you should take.
It does not matter which end you disconnect (either the USB end or the micro USB end). Most people find it easier/quicker to disconnect via the USB end that is plugged directly into your computer.
You only need to leave the device disconnected for a second before plugging it back in.
If reconnecting the device does not solve the issue that you are experiencing, you may want to update the firmware. Simply unplug the KeepKey then hold down the button while you plug it back on. Follow the on-screen instructions to get your KeepKey updated to the latest firmware.