See:

• https://support.mozilla.org/kb/Forgot+my+master+password

You lose all currently saved passwords if you reset the master password.

Hi George,

It is easy to reset but that then you loose all the stored passwords, so before doing that try to list all paswords and sites you sue with passwords, with the passwords that you remmember. Also it may be worth you making a final attempt to try all likley master passwords, including any likley typos you could have made.

• see forgot my master password <-- clickable link --

John