Can't connect to Frostwolf

Last time I've been playing on Frostwolf was about a year ago, I haven't deleted mop from my computer since and now I can't connect to server.
It always saids that the server is offline,name is black,but when i go online its saids that server is working.
Can someone help me with this problem???

You're using the wrong MoP version. Download the current 5.4.8 version from this website.

Frostwolf has been upgraded to 5.4.8, you guys still have old 5.4.2 client, that is why it seems "down" to you
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

Ty guys for a quick response :D