Hey Jacques,
I was surprised that your phone didn't detect any wifi even after all of that. Then I found this and figured that your phone's wifi chip might have died soon after you upgraded to iOS 7. I can only confirm this if you are using iOS 7. If that is not the case, then you should try using wifi with airplane mode on or turn of cellular data.
-You aren't the only one with this problem. Take a look at this link:
http://www.iphoneincanada.ca/news/iost-bug-kills-wifi-iphone4s-users/
-Hope this helped.