Note – this method involves wiping off all data on your phone, including installed apps and the setting you have done. If you want to try another method, which doesn’t reset your phone, you can see it (But, i can’t assure you that it will surely work). If that doesn’t work, this will surely work
Turn off the phone
Long press the upper volume key, menu key and the power key simultaneously
relieve for a fraction as soon as you see the screen display in “Samsung Galaxy Y young” again press the 3 keys simultaneously
Now you will see a screen displaying “Android system Recovery”
select the 3rd option(“Wipe data/factory reset”) using the volume keys and press the centre menu key
6. select the “Yes” option again using the same keys.
7. after some time, it will say, the reset is done
8. just select the reboot option and your phone is UNLOCKED.