Before doing the reset, keep out the SIM card as it affects the contacts on it. It can be deleted so check it before doing so.
1. Turn off phone
2. Wait for 5 to 10 seconds. Hold these keys , volume up and home button and power button for few seconds.
3. Recovery Menu
4. Select “C”
5. Wipe data/factory reset scroll down
6. Choose “Yes”
7. Delete all
8. Then Next
9. Restart your phone
If this won`t work, bring your phone on nearest customer service center in your place.