Trying to access localhost no longer works on my new Macbook air. It used to work just fine on my old Macbook Pro which was also running Mountain Lion. I have tried most suggestions found in other forums, and SU questions. Nothing seems to have solved the issue yet. Any help is greatly appreciated.
I do believe we need more details. Make a summary of what you've tried. What do you mean by that you can't access localhost? Do you mean the hostname "localhost" or can't you even access 127.0.0.1 (which is the ip adress locahost should be bound to)? can you ping localhost and/or 127.0.0.1? Are there any special ports/services (webserver, ftp, etc) that you mean that you can't access? Etc...
But if you can access 127.0.0.1 (even if you can't access the hostname "localhost"), make sure that a line similar to