I was trying to log in to a secure site but get an Secure Connection Failed error. On checking Options>Advanced>View Certificate>Your Certificate, I found that my digital certificate, which is required to access this secure site, is missing. I need to recover the certificate. I have located Cert8.db file. I had also backed up the digital certificate but can't locate the backup copy (I also upgraded to Windows 10 in the meantime)

I would highly appreciate any help in recovering digitial certificate. I don't know why Firefox not import all digital certificate during upgrades (which I had set to to automatic)