It could be an external hard disk, pen drive, memory card, printer ... devices and check if it solves the issue or not. Device Manager mainly displays your devices and drivers at the same time.

Linda File Manager is a free download from the Android App Market, and provides list-view navigation through all the file locations on a device – including USB and SD card devices.

Sick of constantly plugging and unplugging the microSD card between the SBC and an SD card reader ... that lets you swap a card between a DUT (Device Under Test) and your personal computer ...