What exactly happens? Can you turn on WiFi on the phone? Is WiFi enabled on the phone and you aren't seeing any WiFi networks? Do you see networks but can't join them?
WiFi can not be enabled. It first started when I was not able to see any WiFi networks, then I turned off my phone but now the WiFi can not be enabled.
Have you tried "Reset Network Settings?"
If that doesn't fix it, try a full Restore.
Unfortunately, on a phone as old as an iPhone 4, it's possible that the Wi-Fi radio has failed.
this fault cannot be fixed i look my phone to the genius bar at the Apple Store . Reinstalling did not help and they told me that i would either have to do without wifi or get a new phone