I have an old iPod classic that iTunes cannot find, I can't even restore it!?

It will (the iPod) sometimes show up on the desktop other times in iTunes. However when it tries to synch even though it shows it iTuned says iPod cannot be found. Even the techs at an Apple store sais it contradicts itself and could not figure it out. They said it must be the iPod not iTunes because we tried it on several computers at the store. They said "somehow" it needs to be restored, but since it is both there and not there iTunes will not do it. I agree, it does contradict itself. Never the less that is what is happening, stranger than truth or fiction! Hmmm!?

We (Appple techs) tried disk mode and that didn't work. At times the iPod would even "show" itself in iTunes and iTunes would say it was synching but when you looked at the iPod you could tell it wasn't ( it just said do not disconnect) and after 10 to 40 minutes later iTunes would say can't find iPod. We would then have to force quit iTunes because it was hung up and then just disconnect the iPod. The iPod works fine with headphones or a docking station, just can't add (or subtract) anything to it. It completely mystified all the techs in the store and all "senior" advisors on the phone- and that was about 4.5 hours getting tossed to one "expert" or another! Ah well, indeed stranger than life.