Help:Messenger not receiving messages

I made some changes to my Messenger settings to allow wireless connectivity
on my home Broadband connection. Since the changes when I and cabled on my
woirkplace LAN I am unable to receive messages from anyone and they get a
messge cannot be delivered error.

I have removed the additional setting I made but it still doesn't work.

Any ideas on what to try next, I am guessing there is a Control Panel
setting I need to change but have no idea which one.

Thanks

Sparks
.