The answer probably depends on different factors so it might help if you give more info about your home wifi setup. Not sure if anything in the following links will help you out but it won't hurt to see. Some may not be relevant at all, but it's the best I could do with no info other than you asking why your iPhone doesn't recognize your network.
https://discussions.apple.com/thread/1648395?start=240&tstart=0 (if this one takes you to the 1st page of the thread click on page 17...the last post has a suggested solution that may work for you if you haven't tried it)
Also, do you have bluetooth turned on? If so, try turning it off and seeing if you can get your iPhone to recognize the home network. I recall some saying they had to do this...I personally haven't had any issues so I can't tell you if it works or not (my 4s sees my network fine and I do have bluetooth turned on).