Connected to a wifi network but my webpage doesnot opens

Can anyone help to sort out this issue in my lappy.

I have I5 generation Toshiba Laptop , recently am facing a problem is that when I open my browser ( chrome / mozilla / internet explorer ) none of the websites is getting loaded at all.

It takes normally more than a minute to load google search engine also.

I have 20 mbps speed wifi connection .

Can you please help me to sort out this issue in my laptop. I am facing it for past two days.