I would start with
Run this to help if it identifies the cause
Have you tried on another computer to help determine if you have a computer or iPod problem?
1. Press and hold (& continue to hold) BOTH the Sleep/Wake button & the Home button.
2. Continue to hold BOTH (ignoring any other messages that may show) until you see the
Apple logo on the screen.
3. Release BOTH buttons when you see the Apple logo and allow the device to boot normally.
if no result try a different usb cable and port and try this
open itunes on computer
plug cable into computer not iOS device
turn phone off
hold home button and plug cable into phone. do not release home button until an itunes graphic appears on device.
look to computer should have message about recovery mode click ok and restore
if u need an article see