Q: Itunes cant identifty2nd Gen  iTV to enable Software update

At first try to restart Apple TV How to restart your Apple TV - Apple Support

Then you can try to restore Apple TV via iTunes. Restore your Apple TV through iTunes - Apple Support

Hi. If you really have an ATV 2, not the current ATV 4, the last software update was version 6.2.1 in September, 2014. So there may not be any new update.