This should be in game help. *moofz*
I think I saw another thread about this earlier in here. I'm afraid I havn't been on much since I was sleeping yesterday, and I'm not even at home right now.
These things has happened before though, it usually sorts itself after a while if you just are patient.
Maybe there was too much load inside the plains for a long amount of time causing a crash. I'm sorry for this happening, but I don't know why.
I think you should be able to create a new char and play in maps like ficho and bonfire still though. That works until plains works again.