just checking, does your wifi use a user name and password? if so make sure you you write it correct in your phone, if you already did. then write again your username and password of your wifi box just to make sure.
if your problem with the wifi then here a few things to do :
check your wifi connected right to internet service check your wifi antenna cable connected to wifi box correctly. check the light in your wifi do you see it flashing even slightly it means it has connection.
if nothing works your wifi box should have 1 or 2 buttons at the back click the one on left for 5 seconds i should restore defaults of your wifi if something was wrong.
it should work well if you tried these checks.