Can't access facebook; error message says ERR_CONNECTION_CLOSED

Hi everyone, I can no longer access Facebook. The error message says "This webpage is not available. ERR_CONNECTION_CLOSED". I've cleared out my history, cache, cookies, and then restarted my computer, all to no avail. I can access other sites, and Facebook works just fine on my sister's laptop which also uses the same router. I've been using Facebook for years and this is the first time it happened. How can I fix this problem? Thanks in advance!