my ipod nano 2nd generation stopped being recognised in itunes. using windows 8, all our other ipods are fine

My ipod nano 2nd gen just stopped being recognised in itunes. I'm using windows 8.1..and not had any problems with ipod touch 5th generation or nano 7th gen.

The ipod charges up as indicated by the battery icon but not being recognised at all in itunes or as a connected device or drive on my PC. was working fine the day before then just stopped. I can still listen to the ipod but obviously not load on new songs as not being recognised.