You’ll need latest version of NSSpro (Nokia Service Software), Nokia PC Suite/Ovi Suite, Nokia connectivity driver package.
1. Connect your phone to computer via USB data cable, and choose PC Suite or Ovi mode.
Ques. How to choose Ovi Suite in Locked Mobiles?? [Tested]
Solution. Install Nokia PC Suite/Ovi Suite, and Nokia connectivity driver package on your system.Remove Micro SD or SD card from your mobile and then connect it to your system close any popup notification immediately, saying ‘Nokia USB connecting on mass storage’ or anything else. Your phone now automatically gets connected to Ovi suite.
2. Open NSS pro with administrator privilege.
3. Click Read Info and you will see your phone details on left side.
[This step is only for ensuring that your phone is connected with NSS Pro]
4. Choose Test Mode on bottom right of the screen to enter the phone in test mode. And click the right arrow button (>) to reboot phone. Under Factory Settings, choose Full Factory and click Reset.
If it’s not working you may try below given steps
Little risky but working
[Click ">" button and after 2-3 seconds quickly remove USB cable and re-insert. After a gap of 3-4 seconds the phone should go dark, but it’ll not actually switched off, now you'll see written "test mode, NOKIA" in the center of the screen. You are now in Test Mode.
Select "Full Factory" and then click "Reset". When "init connection" appears removes the cable and re-insert. The phone will reboot and the defaults will be reset.]
Note:-You may try something different or your own steps ON YOUR OWN RISK ,even a single incorrect step may damage your phone very badly.be careful.