The Cook'd and Bomb'd forums can be found at https://www.cookdandbombd.co.uk/forums/ .
If that link doesn't work for you, then you have probably edited your hosts file at some point to hard-code the IP address for www.cookdandbombd.co.uk .
The relevant line in your hosts file will look something like this:
You will need to remove this line to continue.
Guides to editing hosts files on different systems can be found by searching on the internet, but here is a reasonably good one.