I wasn't playing here for some time because of some problems, and now that i'm back, i can't connect to Frostwolf realm, it's like every time it shows Frostwolf is offline, and i tried it with my other accounts but its the same! :(
Frostwolf has been upgraded to 5.4.8, you still have old 5.4.2 client.
So now you have 3 different options:
1) go here: https://www.warmane.com/download and get full 5.4.8 client by selecting "Mist of Pandaria"
2) or by selecting "MoP minimal", it is a 16MB installer which let you play and download the game at same time
3) if you are using 5.4.2 WITHOUT WoD models then you can Upgrade it to 5.4.8 by following this easy guide: http://forum.warmane.com/showthread.php?t=319716