Sansa Fuze with Rockbox formatted by mistake

Go back a step. It may still just be a bad cord. 

The charging connection and data connection are separate pins. One may work and the other may not.  

If you’re in the USA, you could get a new generic cord from Amazon for under $5 and try it. 

http://www.amazon.com/Cable-SanDisk-Sansa-Series-Player/dp/B0019N6AN8/ref=lh_ni_t?ie=UTF8&psc=1&smid=A19R3BN6ZSO9A1

I forget where I got my replacement cord, but I have gotten stuff from SF Planet and they’re legit. (I’d watch out for the super cheap sellers shipping from China.)

Cellphone accessory places might also have the Fuze cord–which is exactly the same as the Sansa E200 series cord.  

http://www.amazon.com/Sandisk-Sansa-E200-Charge-Cable/dp/B000NKCSUC/ref=sr_1_1?s=electronics&ie=UTF8&qid=1378266760&sr=1-1&keywords=sansa+e200+cord

Of course, you can also just keep loading stuff into the external card too.  Just don’t get an iPod cable–they fry Sansas.