Iphone 5s iOS 8.3 Wifi Issue

Hello

My Iphone Used to work with my wifi perfectly but yesterday my wifi went down so i started 3G network to continue my work

but again today it my wifi went up and i logged in iphone 5s

but its not working it used to work

LIKE : I used to get whatsapp messages without opening the actual app facecbook messenger too.

and icloud server saying verification failed and cant loggin eventhough all the details are correct

BUT WHEN I USE IT WITH 3G IT WORKS GREAT.. BUT NOT WITH WIFI NOW

KINDLY TELL ME SOLUTION SO THAT I AGAIN START WORKING WITH WIFI

P.S rest of the things working fine like web surfing when connected to WIFI

and laptops and other devices working grerat with WIFI