木人仔

where are you from？？it feels like ISP problem or DNS hijacking, if it is an ISP problem try to contect your ISP, they might block the IP of fb, and the reason normally is politics problem, and hope they can fix it,
if that's not an ISP problem,try to use other friend's network, to connect to fb, if it can connect to fb obviously router issue,go to internet find some ip setting of router
if you had tried another network, and still can't connect to fb, your pc might got some virus or Trojan, use antivirus software to scan your pc asap,  if the antivirus software can't find any thing, suggest that re-install your windows