You might be using the same IP address with someone else and someone using the IP address which you are also using did something for wiki to disallow access to what you are trying to do
Depending on what type of IP you have, whether it be a static IP which you cannot change and you will always have that same IP
Or if you happen to have a dynamic IP address, you chould possibly reset your router or modem and when reconnected a new IP would be assigned to you
If you are not sure what type of IP you have, you can try and disconnect your internet access by removing the cable to your computer that gives you internet access for about 30 secs and then re-connect, after about 10 sec or so, your connection will be re-established and assigned an IP address
Now try again
If same result, you would have a static IP and you try and contact wiki
Have you tried to create your own account?
Log in / create account - Wikipedia, the free encyclopedia