i have a 3g iphone with his last possible OS 4.2.1. After update of this app is not possible use it. How to download and install the old correct version?

hace 10 años • actualizado por hace 10 años • 0

i have a 3g iphone with his last possible OS (4.2.1). After update of this app is not possible use it. How to download and install the old correct version?
Many thanks