Help with irc?

I'm trying to connect into the 4chan irc server, and I can get in fine although whenever I try to type a message I'm greeted with "#4chan Cannot send to channel." This happened suddenly, and odds are I clicked one of the mode keys in leaf chat. Different clients have the same problem, so what can I do to fix this?

Learn to irc, faggot.

Register your nick and identify. To learn how to register, type
/msg nickserv help register
Once you register you can identify (basically like logging in) by typing
/msg nickserv identify yourpasswordhere