1.Go au menu
2.Puis sur les "Paramètres"
3.Maintenant tap sur l'option "Vie privée"
4.Here aller à "Data Factory Reset"
5.Maintenant robinet sur "Réinitialiser le téléphone"
6 Enfin taper sur «Effacer tout» pour confirmer la réinitialisation
>>>>>How to reinstall the software on Sony Ericsson Xperia Active ST17i?
1 From you Home screen,Go to the Menu
2 Find and tap Settings > Privacy
3 Tap Factory data reset
4 To erase not only internal storage but also other user data such as 5 pictures and music, mark the Erase SD card checkbox.
6 Tap Reset phone
7 To confirm, tap Erase everything