problem need help

My game stucked in molten ...i hadn't played since3 years ago..so when i open the game page it seems that i am in ragnaros server which is doesn't exist..what can i do??i must download the whole game? beacause when i put username and password says unable to connect

Change your realmlist, for starters. The new one is "set realmlist logon.warmane.com". When you log in, you'll notice that all your characters are gone. You'll have to start anew. Icecrown is like the old Ragnaros.