Just wait, I think.
It happened to me 20 days ago and it lasted 2 weeks :sad2:. I think it was an IP ban. I could connect to other realms but not Europe. Reason? I don't know:scratch:, the use of hacks can lead to that but, believe me, I don't use hacks of any sort.
Just to be sure, try to connect to other realms. If it works could be a problem like mine, in which case the only thing you can do is wait, I suppose .