There is no "back door" -- you have to remember it.

(There are password database cracking services offered on various web sites, but I can't really recommend any of them because you really wouldn't want them to have all your logins.)

https://support.mozilla.com/en-US/kb/Forgot%20my%20master%20password

You can reset your Mater Password, but you will lose all your passwords.

I could hv done that but I need my stored passwords!! :'-(

The names and passwords are encrypted with a Triple-DES key that is stored in key3.db and a master password adds an additional level to that encryption. Without the MP it is impossible to get access to the stored names. So if you do not remember that MP then your passwords are lost.

• http://en.wikipedia.org/wiki/Triple_DES - TripleDES (CBC mode)