You can try and reset the player.
resetting a Clip 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.
Some things to check for when your player does not act like its taking a charge.
Make sure that the USB cable is properly plugged in and use the original cable that came with your player.
Computer in Hibernation mode
Make sure the computer isn't entering hibernation or sleep mode while the device is connected. The computer must be ON in order to charge your player.
USB Port 2.0
Make sure the player is connected to a USB 2.0 port (1.1 occasionally causes charging problems).
USB Port location
Try plugging into different USB ports (i.e. USB port in the back of the computer); occasionally the front USB ports have limited power to charge up the device.
Make sure the battery is fully charged. It takes approximately 3 hours to fully charge the battery.
Depending on what Sansa player you have, make sure it's up to date with the latest firmware.
AC charger (optional)
AC chargers (sold separately) have a 500-1000 milliamp max output, which provides much better charging ability than a USB port.
I have some tips posted here on MP3 players and their problems.
MP3 player not found by computer
SanDisk Mp3 Player Frozen