Hard Reset SAMSUNG i559 Galaxy Pop

First method:

1. Turn off your phone.
   
2. Next hold and press Volume Down + Menu key + Power button.
   
3. Then select "wipe data/factory reset" using Volume down button to scroll option, and Power button to confirm operation.
   
4. Now choose "yes" option and confirm that with Power button.
   
5. After that select option "reboot system now".
   

Second method:

1. First check, that your phone is on.
2. Then tap this code: *2767*2855#
3. Next wait until your phone restarts.

WARNING !
Hard Reset will erase all of your data
All described operations you are doing at your own risk.