Computer won't recognize Cowon J3

[Noex]

I bought my Cowon J3 to work and had videos on there I wanted to watch.
When I turned it on the device was low on battery.

I looked around my work place for a connector use to charge it. Found one that belonged to a samsung phone and tried to use it to charge my Cowon J3. Didn't work, what it did was make the J3 freeze. I had to do a hard reset to make it work again.

I take it back home to add more music it to it using my own USB cable that came with the J3 except my computer won't pick it up. Neither my family computer or my PS3. All it does is charge.

I tried switching between MSC/MTP, I also tried hard resets a couple of time but my computers doesn't pick up the J3 when it is connected.

Can I get advice on this? I'd appreciate it.