Cant Connect to servers

Hi
I cannot connect to servers.
It say unable to connect, etc
My realmlist has correct value as before.

Do I need need anything other than WoTLK 3.3.5 client?

coz before I knew there are servers like warname. I used to have a client BC to play offline.
there were some other software needed to be run for this.
I deleted them couple of days ago
maybe this is the problem
I dont know
But I have correct client version 3.3.5 installed on my computer as before.
everything looks fine except i cant login