Cannot connect to localhost

Hello, I recently change my ip from dhcp to static but I just noticed that when I try http://localhost:901 or http://localhost:631 I get a "cannot connet to localhost" error. This used to work for me so I think I messed up by mistake a loopback setting or a service not running??? has anyone had this problem before?

thanks

I assume you are running some sort of a Linux here..

First, check your /etc/hosts file and see what it says about localhost. You should have an entry saying that 127.0.0.1 is the same as localhost.
Second, run "netstat -tlnp" to get a list of processes listening for network connections. You should have cupsd listening on 0.0.0.0/0:631 for example.

Actually http://localhost/ works on Windows too, assuming the service is
properly configured to listen on *:80, or in your case *:901

Verify your config for the service
eg:
Listen 0.0.0.0:80
Listen 0.0.0.0:901