Since three days itunes cannot identify my ipod and my ipad

I've added music and video's to itunes and tried by connecting the cable between computer ipod and/or ipad to synchronize the library in itunes.

In the left column in itunes after that cable connection there is no recognision of the device ipod and/or ipad (as I'm used to). A message appears in Dutch. I will tranlate the message: Ipod cannot be identified, try to reconnect by reconnecting the cable. The same message appears at the ipad device.

Please help, I'm desperate.