why do my internet explorer can't access social networking sites such as facebook and twitter except multiply?

[R4 DS]

Perhaps your router settings are set in a way in which these websites are blocked? Try contacting the one responsible. Try using other laptops within the same network. Do these websites load? If not, then the problem is probably that the websites are blocked from the router settings. Otherwise, they might be blocked in your entire country, which I find very unlikely.
Another thing you can do is to try getting a different browser like Chrome or Mozilla, and see if the websites work on the new browser. If yes, then something's wrong with the IE settings. Reset them, and try again.
However, if they don't work on the new browser as well, then again check the router settings.
Hope I helped somehow.