If your iPod won’t show up in iTunes, it could just be that it needs to be reset by pressing the Home and Sleep/Wake button down at the same time until the screen goes black and the Apple logo appears. It that doesn’t work it might help to put the iPod into Disk Mode. To do this, start to reset your iPod, then as soon as the Apple logo shows up either hold the volume down and volume up buttons at the same time until it enters Disk Mode, or if you have a click wheel on your iPod, then press and hold the Select and Play/Pause buttons until the Disk Mode screen appears.
If resetting or putting your iPod in Disk Mode doesn’t help it show up in iTunes, then there are a few other issues that might be happening. One of them is that there could be a problem with your dock cable that isn’t allowing the iPod to show. If you have another cable that you can use, try that, or try to plug the iPod into a different USB port. If you see that the port is working but the iPod still isn’t showing up in iTunes, it could be that you have a problem with the software on your computer. If you know that you are having no computer problems, then you might have a hardware problem with you iPod that requires repairs. If so, contact the Apple Genius Bar to see if you should take your iPod in.