This the image.

Did you ever install this extension:

https://addons.mozilla.org/firefox/addon/master-password-timeout/ or is it this one: https://addons.mozilla.org/firefox/addon/master-password/ or this one: https://addons.mozilla.org/firefox/addon/master-password-timeout-upd/

To bypass extensions, you can start Firefox in its Safe Mode. First, make sure Firefox is fully shut down and does not appear in the Task Manager (Ctrl+Shift+Esc). In particular, make sure firefox.exe is no longer running on the Processes tab. Or you could do this after restarting Windows.

Hold down the Shift key when starting Firefox.

A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Then you can go to the Add-ons page and remove this extension. Either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions. Then find it on the right side and click Remove. That should take effect when you exit Firefox and start it up again normally.

Success?

Sorry, I think it's this extension, I'll update the above link:

https://addons.mozilla.org/firefox/addon/master-password/

The page says:

Current version has an issue that prevents Firefox from unlocking, nothing happens when it's locked and user click or presses a button.
As a work around this issue, press CTRL+N to open new window, then you'll be able unlock it.
As of now I'm struggling to find what causing this. I need your help: http://goo.gl/waq6w

Perfect. I opened it with shift and it got me in via Safe Mode, i went to extensions and removed Master Password. It works great now. Thank you very much kind sir.