Cannot open Twitter, Facebook and Youtube?

[Tim]

Hi all,
I'm encountering a problem that I cannot open Twitter, Facebook and Youtube websites on my pc. And the Twitter, FB and tube apps on my iPad cannot get data either. None of the devices that are connected to our home wifi can access the three websites. Cellphone works fine via 3G signal. I called the internet provider customer service, but they don't nothing. The problem is werid. Can anyone tell me what should I do?
Appreciate it!
-Tim
It's not just me. None of our PCs and mobile devices that are connected to the wifi can access to these websites.

[Leereizt19]

i'm curious someone had palying with you and change the setting of your pc,i mean block them (twitter,facebook and youtube)
you can unblog that by your self :
try this tutorial : http://www.ablog2all.com/2013/02/how-to-...puter.html

if u got same result or it didn't fix, you can add s or double www in URL of them..
example : Https://facebook.com
http://www.www.www.facebook.com