My gpx ml648b won't turn on I have the usb cord plugged in and I don't know if it's charging or not.

Plug the device into your computer with your USB cord. Double click the Computer icon on your Desktop. Then double click on GPX Device and double click again on Removable Storage and double click the Music folder. You should now be able to see all the files you've loaded onto your MP3 player. Simply select the ones you no longer want and hit the Delete key on your keyboard.

are you charging with your computer through the USB cord or did you get an adapter to charge via an outlet?
If charging with your computer, it could be a bad USB port, try the ports in the back of the tower if your using the front and vice versa.
Is the device responsive otherwise? Can you load music and the like while the device is connected? If not your USB Cord could be faulty and need to be replaced.

If you are using a laptop keep in mind that sometimes the amount of voltage required for this device does not always reach the USB ports. Try disengaging the laptop battery for an hour and then reconnecting it.

I think it's safe to assume that either your batter is no good or your cable is no good. You can contact GPX and with proof of purchase you should be able to get it replaced. You can also just buy a new cord or borrow one from a friend if they have it. See if your cell phone charger will plug into the MP3 player as well.
also if you are charging from a laptop be sure that no other devices are plugged into the other USB ports. I hope this helps.

The Player gets it's charge from the USB port. I would recommend plugging your Player in and leave your computer on overnight.
If your player still does not retain a charge, I would contact the manufacturer.

just on plug the machine and turn on then plug back in to the comp. then it should work

Plug it into the computer via the supplied USB cable - will take 3-4 hours to fully charge.

I tried to reset and it didn't work, They way I figured out was to shut it off then plug the USB in. Then the screen shows up where it is sleeping, Then hit the power button one time and in the bottom left the USB light came on and in the top right you can see your battery taking charge. Hope this helps, It took me about three weeks to figure out

all you have to do is turn off your device and hook up your usb cord to your device and to your computer

1. Connect your ML648B to your computer with Windows XP or later.
2. By default your computer will recognize ML648B as GPX MTP Device. (Wait for few seconds to a minute allowing your Windows computer to recognize and install necessary drivers for the device for first time as MTP Device.)
3. Press the POWER button from top of your ML648B, to change it to USB mode connection. You will also see USB on the screen of ML648B. (Wait for few seconds to a minute allowing your Windows computer to recognize and install necessary drivers for the device for first time as USB device.)
4. ML648B will now mount 2 drives, one as Tools (as CD-Drive) and second as Removable Disk (Drive) – under My Computer on your Windows Desktop.
5. Double click & open Tools, and run Setup.exe to start installing Video Conversion Software tool.
6. Select defaults options and finish the installation by clicking on Close or Finish.
7. If asked, click on Continue Anyway on Windows XP or Install this driver software anyway on Windows Vista.

It will if it is a mini-USB plug. The mp3 has the mini-USB cord bundled, and can be used with anything with a mini-USB port. My cell has the same port, so I can charge it on the PC like the mp3, and can use the wall socket charger for the phone on the mp3.