Why will iPhone not allow me to connect to wifi?
My iPhone worked perfectly for months. Recently, however, I plugged my iPhone into itunes for the first time, to download the 3.1 software and tunes to the iPod. Now, my iPhone won't connect to my wireless internet at my home or office. In fact, when I go to "settings," it says "no wifi." How do I get my phone to recognize my wireless router, as it did before?
Is your iPhone on a contract of jailbroken? If you upgraded to 3.1 there are issues where the wifi just dies. It is a hardware problem and just look at one of the many discussions here:
You can try some of the tricks there but I am afraid it can be hard to heal it.
It says "no wifi" meaning the iPhone does not recognize the wifi board anymore. I had this issue on 8GB 1.gen. iPhone and bought a new communication board. I got one cheap(er) on ebay. The battery is soldered to it like here: (http://cgi.ebay.com/Apple-iPhone-2G-Comm...) No sweat to replace it. The hard part is always to open the iPhone.
Good luck and I would spend that money on your iPhone since it seems it is working.
The issue might be either hardware- or software- related.
If it is a hardware problem, your iPhone Wi-Fi switch under Settings > Wi-Fi will be turned off and/or greyed out (unable to be turned back on). This happens especially on iPhone 4 and iPhone 4S running iOS 6 and iOS 7 as the Wi-Fi radio chip overheats. Not much to do here except to take it to the Apple Store for replacement.
If it is a software issue, it can get resolved by cold restarting the iPhone and/or by resetting your iPhone network settings via Settings > General > Reset > Reset Network Settings.