my last solution:
have you installed your windows new again since 1st MoW multiplayer login?
when "NO" start windows application "regedit.exe" and navigate (left window) to key "[HKEY_CURRENT_USER\Software\1C\Men of War]" on right side you can see an entry with your MoW account name/nick and your MoW multiplayer cd-key. use this nickname (without "_") and all your known passwords (from 3 e-mail adress).