You wrote about ""mywi"" - did you actually connect with the iPhone ? (especially - what distance did you have between the device you connected with the iPhone? - and of course - did you try to connect with the router - while you're standing beside the router?)
The first link didn't work - the second one isn't the Wi-Fi antenna
The Wi-Fi antenna looks like that: the connector is number 6 - so check the connection and of course check the contacts. Also, if you bent the connector to much, it could be broken and the result would be no or bad Wi-Fi reception.
Update
I searched my sources a little bit and found a solution posted in a gsm forum by ""MPhoneClinic"" (the mobile phone clinic from melbourne/australia)
I searched for a larger picture of the PCB and marked the part that you have to change
So, the good thing is - you know what's defective. The bad thing is - where to get the part and depending on the tools/skills you have, how to replace it.
But maybe you will find a good repair shop in your area who is able to fix it for you."
"Hi! i was having this problem in my 3g and solved it by doing the following..
install bootlace, install idroid, boot in idroid, turn on the wifi - power off idroid boot on ios 4.x..
wifi working.. i tryed everithing else except for the hardware solution and nothing worked (except for the freezer thing.. that worked for some minutes)..
The following clever little fix worked for me. I think what happens is the heat liquefies a broken solder point enough to reestablish contact. (I used the hair dryer option): http://www.google.com/url?sa=t&source=we...
"hi i am also heaving the same problum but the thing is my WiFi option is in gray light gray colour which means i cant even open it. plz help me out i cant buy an other iphone coz i dont have money
"The light bulb theory apple releases software updates that have hidden agenda to phase out older models forces us to upgrade to newer products. I've had 7 different 3 gs with the same problem that worked fine prior to os 3 series but after any is higher then that series wifi did not work I find that a bit odd
i have the same problem in my wi-fi my iphone 3gs is not searching any wi-fi network i have checked it on 2 or 3 wi-fi connections but it is not searching any of them plz help me if someone can...