Chosen Solution
Hello all this is my first post here. I was reassembling my iPhone 4 and I accidentally left a part out. Now I think this part has something to do with the wifi possibly as my wifi does not work (it can’t find any routers). Here are two pictures, it is a small metal (bracket?) which I THINK goes somewhere in the top of the iPhone. http://i.imgur.com/X92R0GG.jpg
http://i.imgur.com/wbsCcwS.jpg
It is this part in the iPhone 4 which acts as a grounding bracket and aids in the securing of the screw, it will be the reason your wifi will not work. See this image
Complete the following guide and you should see where it should go iPhone 4 Wi-Fi Antenna Replacement If you need any more help just ask. Cheers Brendan Mills