Currently Being ModeratedJan 27, 2013 8:54 AM (in response to minessa)
Try the suggestions here to see if they resolve your problem: http://support.apple.com/kb/ts1559
If these don't work you may have a hardware problem.
Currently Being ModeratedJan 27, 2013 8:57 AM (in response to minessa)
Please can you clarify what won't switch on, the WiFi or phone?
If it's the phone and have recently run out of battery, plug it into a charger, and wait 5 minutes before trying to switch it back on again; iPhones, if they run out of battery when plugged in again sometimes take a short while to turn on.
To connect to a WiFi you will need access to the network key, may also be called the WEP key. This can commonly be found on the bottom of your router or on a seperate card that came with it.