lost PW, Can't get signed on

There is work going on in my house, and workers I do not know, and my "code" book (passwords)is lost, so I reset my computer to password sign on. That PW is not in my code book.
When I signed on, I went to Mozilla T'bird to get email it asks for a password but, I do not know it.
How do I retrieve or change my PW?
Skysarge

 

you need to get the password for whatever mail server you get your mail from.

 

While waiting for reply from server, I played my version of :Guess your PW" and got lucky.
Thanks, 'gun for assist, and i will keep their reply for future reference.
Skysarge