I am sure most of the use USBs and the most prominent thing you will remember about is "Safe Eject" for devices like those. If you get to see Error Code 47 for one such device, it means it's in process of ejection. The full error message for such scenario is :

Windows cannot use this hardware device because it has been prepared for safe removal, but it has not been removed from the computer. To fix this problem, unplug this device from your computer and then plug it in again. (Code 47)

While the process hardly takes any time, but in case it gets stuck, and Windows is still preparing the device for removal or pressed a physical eject button, then follow the below method.

You can either unplug and plug it back in (make sure there is no file copy or move in the process) or you can restart your computer to do a reset for this status.