Solution 1:

Firefox keeps your passwords in your profile, and in most/all versions since v2.0 this data is encrypted.

Check out here: http://kb.mozillazine.org/Profile_folder_-_Firefox for locations of the password files on Windows (various versions), Linux and Mac.

  • key3.db - Key database
  • signons.txt - Previous to 2.0.0.2 - Encrypted saved passwords, requires key3.db to work
  • signons2.txt - 2.0.0.2 and above - Encrypted saved passwords (and URL exceptions where "NEVER SAVE PASSWORD" is selected), requires key3.db to work
  • signons3.txt - 3.0 and above - Encrypted saved passwords (and URL exceptions where "NEVER SAVE PASSWORD" is selected), requires key3.db to work
  • signons.sqlite - 3.5 and above - Encrypted saved passwords (and URL exceptions where "NEVER SAVE PASSWORD" is selected), requires key3.db to work.

Solution 2:

From Firefox Help - Recovering important data from an old profile:

Your passwords are stored in two different files, both of which are required:

  • key3.db - This file stores your key database for your passwords. To transfer saved passwords, you must copy this file along with the following file.
  • signons.sqlite - Saved passwords.

Thus, I would try searching your computer for these two files and checking them out for yourself...

Solution 3:

password forensics has an overview and tools for recovery. The latter is a brute force attack on the master password (if you have it, which you should). The security is as good as your password, basically. This link has more details (same site).