I just upgraded to a Iphone4s and have a home wi fi network. I am having trouble gettingto my home network

I just upgraded to an I phone4s and am unable to connect to my home wi fi connection which is connected thru Comcast Cable / Infinity Network cable system.

I keep putting in the network key. very carefully, have put in the proper security code wpa2, and have contacted Comcast for help. All to no avail. have read

all the online solutions and they are now talking about resetting my router settings????? Comcast tried everything and they said I would have to go lto

apple.for a solution. I was able to get on at a wifi network at my daughters home, with no problem, so is it the phone, the settings, the modem/router or Comcast, or

Apple, or the phone or what. Sadly, I don't have any hair to pull it out. At my wits end. Can someone help me?????