I had the same problem on a Contivity 600 and when I called Nortel support they told me there was no password recovery for the system. The Contivity had to actually be sent in for repair in order to recover from a lost password. I'm not sure that this is the same on the Contivity 100 but it may be. In my case, after three days of trying I finally guessed the password.
Good Luck,
Googer