If the Zune software cannot detect your Zune and you’ve done the obvious (disconnect and reconnect the device, reset the device, and restart your Zune software) then you might need to re-register the Windows Media Device Manager. To do this . . .
1. Disconnect your Zune device and close the Zune software.
2. Click Start and select Run.
3. Type regsvr32 “C:\Program Files\Zune\zunesp.dll”.
4. Click OK.
You should then see a message reading: DllRegisterServer in C:\Program Files\Zune\zunesp.dll succeeded.. Click OK start your Zune software and connect the device.