1. Turn On the Xperia ST27i - swipe to unlock screen
2. Tap "Emergency Call"
3. On the dial pad, dial *#*#7378423#*#* - you should get a menu after 5 seconds
4. Select "Customizasion Settings"
5. Select "Reset Customization"
6. Confirm selection by taping "Reset customization and reboot"
7. Petiently wait for the Xperia ST25i to fully load/reboot
8. You Sony Xperia ST25i will be reset with all previous user customization and data erased. This erased customization will include your forgotten scren lock pattern or pin.