If the server you were banned from was an official Napoleonic Wars server, please post your unban request
here, using the proper format as defined
here.
If the server was a server run and administrated by an unofficial host, please try to find their server threads on this
list of threads for NW servers, or in the
Servers board. Once you have found it, post your unban request in accordance with the server's guidelines.
Should that fail, I wish you luck in contacting the server owners through other means.