Go
Computer > C:\programfiles\world of warcraft\data\engb

Select your realmlist.wtf , and open it with notepad. ( make a backup 1st).
delete the text in it and post.

set realmlist us.logon.worldofwarcraft.com
set patchlist us.version.worldofwarcraft.com
set realmlistbn ""
set portal us Save.

and start wow by wow.exe , or laucher.

also delete your cache but its not a must.

2nd method.

Copy your wow > change the realmlist.wtf of that wow so you dont have to keep changing realmlist.

set realmlist eu.logon.worldofwarcraft.com
set patchlist eu.version.worldofwarcraft.com
set realmlistbn ""
set portal eu

For US clients:

set realmlist us.logon.worldofwarcraft.com
set patchlist us.version.worldofwarcraft.com
set realmlistbn ""
set portal us

basicamente borra el realmlist y pon el de us, tmb se recomienda borrar el cache