No instance servers are available

Q u o t e:
keep trying to log into server on char select i dc'ed in an instance and now can not log in.

That can sometimes happen if you disconnect inside an instance, basically - where you were no longer exists.

Sometimes logging into another character can help, or you could submit an ingame petition and ask a Game Master move that character because it is 'stuck' in a dungeon.

A bit earlier today someone reported that a reset UI (or at least a partial one) also seemed to help. If you'd like to try that as well, I'll note the directions below.

To do a full reset UI, you will want to save your addons in another spot if you wish to preserve them.

Then rename/delete or move your WTF, Cache and Interface folders while WoW is shutdown. Reboot your system.

Note, if you are running Vista make sure your permissions are set so it does not undo your changes.

More detailed instructions for different operating systems, including Macs are here.

http://us.blizzard.com/support/article.xml?articleId=18761&searchQuery=reset%20UI&pageNumber=1