My computer doesn't recognize my gpx ml648 mp3

I am going to type up what the owners manual says for this:
1. Try running Windows Update to see if there are any Service Packs they have available. You can do this by going to www.windowsupdate.com

2. Scan for hardware changes. To do so, open Device Manager. This can be found by right clicking on My Computer. Choose Properties from the menu that appears, In this System Properties menu, click on the Hardware tab. From the Hardware tab, click on Device Manager. Within Device Manager, there should be a listing for Portable Devices. If there isn't a listing for Portable Devices or the listing shown is highlighted with a question mark, right click on Universal Serial Bus Controllers and select Scan for hardware changes.
3. If no devices connected to a USB port can be recognized, try connecting the mp3 player to a different USB port.

Also, if you are using a USB extention cord - stop. make sure the cord from your player is directly connected to your computer.