Apple iPhone 3G 8GB gives "No WiFi" error

I have had an iPhone 3G 8GB since April 2009. This morning I noticed that it would not connect to my DG834 ADSL router/WiFi access point. I discovered the WiFi setting (Settings/WiFi) to be greyed out and not accessable and under General/About/WiFi Address that there was no MAC address. I powered it off and on since plenty of previous issues have been resolved in this manner - but not this one.

I then did a soft reset (Top power button and home button held in together until the apple came up on screen and I put in my passcode and PIN. This enabled the WiFi setting and returned the MAC address in General/About menu but device still does not seem to connect.

Is this a hardware failure or is it possible for a virus to have disabled the WiFi? It has been working well up until now without a signal degrading so it seems strange.

Regards
Paul

1. Did you recently upgrade the iPhone's OS?
2. It's most certainly not a virus, you can relax about that
3. Has your router's WPA key etc not changed?
4. Do you have other WiFi devices successfully connected to the router?

Also, did you drop the phone perhaps? Not being able to read the Wifi module's MAC address sounds like a hw fault to me, therefor it keeps the WiFi options unavailable if it cannot communicate with the WiFi module itself.

Have you restarted your router? I had the same problem just the other day with my mac not finding my wireless router. I restarted the router and all was fine after that.