atish kumar, a hard reset will help you with that.
Steps:
- Make sure that your Samsung S6102 Galaxy Y Duos is Off, And has no SIM or Memory cards are inside.
- Take out its battery for 10 seconds, Then put it in again.
- Press and hold Volume Up + Home Keys, Then press Power.
- Keep pressing the above keys until Samsung logo appears,Then release all keys.
- Wait until you are into Factory reset / System Recovery menu.
- Use Volume Down key to scroll down and select Wipe Data / Factory Reset option.
- Use Power button or Home key to confirm the operation.
- You need to use the Volume Down key again to select "Yes -- delete all user data"
- Use Power button or Home key to confirm the operation one more time.
- After performing the hard reset, Select Reboot System Now option, And confirm it using Power button or Home key.
- Now the phone will reboots, Wait for it to be fully on and then you can start using it.
Notice: The Hard Reset / Factory Reset operation will '''delete everything that is saved in your phone's internal memory'''. From [http://www.tsar3000.com/Joomla/index.php?option=com_content&view=article&id=991:how-to-hard-reset-samsung-s6102-galaxy-y-duos-using-its-hardware-keys&catid=57:how-to&Itemid=104|here]