My mp3 was on but now it won't come back on or charge.

Try and reset the player.
Reset the player:
1. Slide and hold the Power switch up for approximately 20 seconds.
2. Release the Power switch.
3. To turn the player on, slide the Power switch up then release instantly.

Then try this
Connect the player to your computer.
The screen on your player should turn on, show 'Connected' and indicate the battery charging or full.
- If the player does not turn on try other USB ports or on another computer if one is available. Make sure you are connecting directly to the computer USB port and not to a Umy mp3 was on but now it won't come back on or - 2_bing.gif src="/uploads/images/2_bing.gif" alt="2_bing.gif" class="h_mi" />.
- If there is nothing showing on the screen and the player does show up in as a storage device in an explorer window, then the players screen is just not working.

If you receive the error "USB Device Not Recognized" on the computer, the player is most likely failed. Additional troubleshooting is unlikely to correct the problem.
<<<<< BUT TRY THIS FIRST >>>>>

Check the Device Manager
1. Right-click My Computer, and select -- > Manage.

Click Device Manager on the left pane.
NOTE: Sansa MP3 Players can connect to your computer in MSC or MTP mode.
MTP mode is the recommended and default my mp3 was on but now it won't come back on or - 2_bing.gif Sansa Players when used with Windows OS.

*** See This Tip Posted here ****
Solve your MP3 Player Connection Problem.

The Sansa player will show up on Device Manager's right pane as:
1. USB Mass Storage device (if the player is set to MSC)
2. Portable Device (if the player is set to MTP mode)

If there is a yellow exclamation point (!) or question mark (?) beside the device, try to refresh the drivers.
Refresh the drivers
1. Right-click the entry with the error mark, select Uninstall.
2. On the top menu, click Action then select Scan for hardware changes.

NOTE: If a device with yellow exclamation point (!) continually appears and disappears, then the player is most likely failed. Additional troubleshooting is unlikely to correct the problem.
>>>> BUT TRY THIS <<<<<<<
Connect using MSC mode
Connecting in MSC mode will help determine if there is a problem with MTP mode or with the Auto Detect mode feature of the player. You can use Forced MSC mode or switch the player settings to MSC.
Verifying and changing the USB mode of the device to MSC or MTP From the Main Menu, select Settings > USB Mode.