Hi Girliegrl and welcome to the forums.
When you say you cannot view the artwork on the iPod touch, am I correct in thinking you cannot view the artwork when using the iPod itself (e.g. when using Cover Flow), rather than trying to view the iPod's artwork through iTunes? If so, you could try a couple of things. You could
switch off the iPod touch and then switch it on again; you switch off the iPod touch by pressing and holding the Sleep/Wake button until a red slider appears, and then sliding it. When you switch it on again, see if it has sorted itself out. If not, trying wiping the iPod touch clean and re-syncing from scratch. It might sound drastic, but it has been known to work!