You can delete the logins.json and key3.db files in the Firefox profile folder if the chrome URL (chrome://pippki/content/resetpassword.xul) isn't working.

You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox

This does not help me to reset the Master Password

What do you want to do?

If you want to change the master password then you can do this in "Options/Preferences > Security". If you do not want to use a master password then leave the fields for the new MP empty.

If you do not remember the master password then you have two options:

• use this chrome URL: chrome://pippki/content/resetpassword.xul and click the Reset button
• delete the logins.json and key3.db files in the Firefox profile folder

Both these methods will cause you to lose all the passwords.