Hi,
1. Have you made any changes to the computer prior to the issue?
2. What is the exact error message you receive?
3. When exactly do you receive the error message?
Method 1: Follow the steps provided below to update ‘Teredo Tunneling Adapter’.
a) Press ‘Windows + R’ key and type ‘devmgmt.msc’ and click ‘OK’.
b) Click on ‘View’ on the menu bar and select ‘Show hidden devices’.
c) Locate ‘Network Adapter’ and expand the same.
d) Right-click on ‘Microsoft Teredo Tunneling Adapterand select ‘Properties’.
e) Click on ‘Drivers’ tab and select ‘Update driver’.
Refer the following link to update the drivers.
‘Update a driver for hardware that isn't working properly’
http://windows.microsoft.com/en-US/windows7/Update-a-driver-for-hardware-that-isnt-working-properly
Method 2: If the issue persists then, uninstall and reinstall the network card drivers and check if you’re able to connect to the wireless network.
Here are the steps to uninstall the network card from Device Manager:
a) Click on ‘Start’ and click on ‘Control Panel’.
b) Click on ‘System and Maintenance’, and then click**‘Device Manager’**.
**Note:**If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
c) On the Device Manager window, look for the network card and let us know if you see any yellow exclamation mark in front of the Device.
d) Right click on the network card and select ‘Uninstall’.
e) Re-install the latest network drivers from the Manufacturer’s website.
You may download the network card drivers from the following link.