Try the following:
1) Disable any firewalls, if this doesn't work, move on
2) If you're using wireless, disable the wireless radio and hook your laptop directory to the router with the ethernet, if that works then there's something wrong with your wireless adapter.
3) If you don't have an extra ethernet cable or don't want to hook it up via the ethernet or you did hooked it up via the ethernet and didn't work, then disable the wireless security of your router and connect to your wireless router without any security. If you're able to browse to those sites then, then there's something wrong with your wireless adapter.
4) If either 2 or 3 works, try updating the drivers of your wireless adapter, if either 2 or 3 doesn't work, try updaing the firmware of your wireless router.