there are many many wires that connect the mp3 to the computer but only some actually transfer data across. for example, the wire that comes with the product is good, but another one that looks identical may not work. Also, after a bit, the wire may get stretched or bent and cease working even though the mp3 player itself is still fine. you can sometimes buy a new wire and this will then work fine, at least it may help you be able to copy the files to the computer, and it may even allow you to then reboot your mp3 device or do something else to restart it successfully.