Question : Problem: secret password

I have two kind of switches 3500 series and 2950 series. both of them have enable or secret password I don't know the password and I'm using the console line how can I access the configuration mode?

Answer : Problem: secret password

If you can lose all configuration this is method how to reset to default configuration:
http://www.cromwell-intl.com/tcpip/switch-programming.html#breakin