Steps to the Firefox password reset :

• To access the menu panel, click the menu button.
• Next to Sync and save data, click Sign In.
• Fill in your Firefox Account email address on the Sign-in screen and click Continue.
• Click Have you forgotten your password?
• You'll be prompted to enter the email address linked to your Firefox account. Firefox will send you an email asking you to reset your password.
• To change your password, follow the instructions in the email you received.
• Remember to update your password on all of your synced devices after you've signed in with your new password.

Read More : How do I unfreeze my Firefox browser?