Nowadays, most external devices are conveniently connected to a computer using the USB ports.eg USB keyboard,USB mouse,memory stick,external harddisk,USB modem,flash disk,playstation devices etc. Some USB devices like flash drives should only be removed after stopping it, otherwise the USB device may be damaged and data lost. It is recommended to connect USB to the ports using USB cables; otherwise forcing USB to the port will cause USB damage. Some times, the USB device is not recognized by the computer due to a number of reasons.