So I was trying out different commands, and I typed /ch help, thinking it would tell me about the /ch command, but instead, it transported me to the chat room 'help'' where no one was around. My username became green, and I couldn't chat to anybody.

Is there a way to return to the original chatroom? Because this really puts me off playing multiplayer. Thanks in advance.

The /ch command is short for /chat. Which takes you to the name of the server you put after it, but you can only chat there. In this case you were just sent to the server named help because thats what you typed in.
This is used for being in multiple rooms and once by using /addtab [name] going to the tab and typing /chat [name]
The green name just meant you were the operator of the server, as you created it.

You typed a wrong command,
Go here: http://forum.toribash.com/chat_view.php?channel=support

for support and go here to veiw all chat rooms: http://forum.toribash.com/chat_list.php

PM me for more questions..