My facebook website is not opening. It shows that ur facebook certificate is not valid. server presented a certificate that is not yet valid. No information is available that the certificate can be trusted.
Sounds like it's not your certificate, but your browser reporting that it can't validate the certificate that Facebook is presenting. This could be because you are being attacked and sent to a fake site, or because your root certificates are stale. Have you done a Windows update lately, and accepted the root certificates?