If a desktop, try a USB port on the back of the computer.
Try another USB cable.
This advice from LagunaSansa in this thread worked twice for my e130:
"Try taking the battery out of the Sansa. Let the Sansa sit for 10 minutes. After 10 minutes, hold down the power button for a minute or so. The battery should not be in the player yet.
Next, put in a fresh AAA battery and try turning it on."