my ipod is suddenly not recognized in itunes

my ipod is detected in itunes but can not be identified properly, I reinstalled itunes twice, checked the detection and changed the name to what the instructions said to re identify it and these things have not worked. My cable works fine on everything else my ipod connects to so I dont think that's it Just a few minutes ago it actually recognized it and was allowing me to sync or at least select music to synce but it did not it just erased what I had on my ipod. now it wont recognize it again