The Zune Pad on my 80GB Zune was unresponsive for a day or so and a normal reset or restore didn’t work because they require the Zune pad to be working.
This worked for me, give it a try:
1) Plug Zune in computer via USB
2) Go to the Zune Software
3) Click Settings
4) Click Device
5) Click Player Update
6) Click Install Games (button)
The software will be installed and when the device reboots it should be functioning.