You could try the procedure below to reinstall teredo and get IPv6 protocol working again.
Teredo Tunneling Pseudo-Interface Reinstalling in Windows 7
1. Temporarily disable Firewall and third party antivirus program on the computer for a test.
2. To verify relevant services..
a. Click "Start", type "services.msc" (without quotation marks) in Search Bar and press Enter.
Note: If you are prompted for an administrator password or confirmation, type your password, or click Continue.
b. Scroll down and navigate to the following service. Right click the "Peer Networking Grouping" service and choose Properties.
c. Please check if the service is started; if not, click the Start button and see if it works.
d. You may also choose Automatic next to Startup type.
e. Click OK.
f. Please repeat the above steps with another service: PNRP Machine Name Publication Service.
3. Modify IPv6 registry key to enable IPV6
a. Click Start, type regedit in Search Bar, and then click regedit in the Programs list.
Note: If you are prompted for an administrator password or confirmation, type your password or click Continue.
b. Locate and then click the following registry subkey:
c. Check whether the "DisabledComponents" registry key exists. If so, let's move on the next steps.
d. Double click the "DisabledComponents" registry key and modify the value to 0.
(If the key doesn't exist, please create the key named "DisabledComponents" without the quotes, above and assign the value 0)
e. Exit Registry Editor, and then restart the computer.