I tried a reset option in my phone and it asked for the permission and restarted. From then phone showing two gears spinning. It's still there for last 15 hours. I tried all known reset methods with keys. But it's still not fixed.
Nokia recently released their NSU for Retail tool. Follow the instructions at WPCentral's guide, it's a fairly automated process. I had a phone (Lumia 920) that was bricked for two months that was fixed by this approach.