Both my computers aren't reading my removable disk?

Everytime I plug my Mp4 into my computer using the usb cord item into my Usb port, it doesn't read, but i had other things surrounded by the same port that worked, could someone relieve me with this problem?

Both my computers aren't reading my removable disk?

Install driver for your selective removable disk... Your system may not able to identify your device... So better try after installing driver cd for your removable device...

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