ipod in recovery mode but will not update

I plugged in my ipod only to be informed there was an update for it so I clicked on update,it seems to have updated almost all when it stopped with uknown error occured could not update.Now it will not openswitch on at all and if I connect it to the imac all I get is the itunes symbol and the usb wire symbol plus the message on itunes saying ipod is in recovery mode restore ipod so I click on restore and update and get the following message the ipod could not be restored at this time because ipod software updater could not be contacted or is unavailable at this time.this has been going on for over a day now with the same message.

Any help would be most grateful.ps I have the latest itunes installed and do not have any antivirus software installed.