after upgrading iphone4 to ios 7.1.2 caused in unconnecting to interent, who's can tell me how to do

iphone4 16g ios 7.1.2

after upgrading iphone4 to ios 7.1.2 caused in unconnecting to interent, just received the message from my email address taught me how to recover to interent again, (1) general -- reset -- reset all settings, if doesn't make, try (2) general -- reset -- reset networking settings then your WIFI re enter your password. all followed the step but finally failed. anybody knows how to recover to interent again, please let me know, thanks.