Windows 7: Teredo : media disconnected ?

You say there is a box for a value, What the Property Label, is it MAC Address?

Can't be blank.
What value can I enter there?

You got yourself into a bit of a fix.

You could try launching the task manager and looking at the application list. Select the entry that shows the properties of the adapter and click "End task".

I just don't know what task I can ended

At this point why not just reboot the PC?

Doesn't help to reboot.

What happens when you reboot?

Also try uninstalling the interface, then reboot and let Windows re-detect it.

I uninstall. Reboot, but windows don't re-detect it.
Where can I download it?

You don't need the Teredo adapter unless your doing Homegroups.

Does your other network functions like internet access work ok? If so then just ignore the Teredo adapter.

It was my understanding that Teredo is mainly used for Remote Assitance behind a NAT device.

But this goes into more detail about it..... Teredo tunneling - Wikipedia, the free encyclopedia

Teredo is a tunneling protocol designed to grant IPv6 connectivity to nodes that are located behind IPv6-unaware NAT devices.

More succinctly,, it means,,, "The idea was that the protocol (Teredo) would pierce holes through NAT devices"