Hi, If the Windows version has [http://windows.microsoft.com/en-US/windows7/Previous-versions-of-files-frequently-asked-questions Previous Versions], you can try to enter '''%appdata%''' in the '''Run''' (Windows key + '''R''') box, right-click an empty space in the folder > '''Properties''' > '''Previous Versions'''. Next '''Open''' an older '''Mozilla''' > '''Firefox''' > '''Profiles''' > '''*.default''' folder and copy '''cert8.db''' and /overwrite it into the same folder structure after installing, starting and exiting Firefox. If there are more folders other than the *.default, you may have to copy/overwrite from each previous versions, start Firefox each time and check. You can open your current Firefox profile folder via Firefox after installation to copy/overwrite: '''Help''' ('''Alt''' + '''H''') > '''Troubleshooting Information''' > '''Show Folder'''. If Previous Versions feature is missing then you may have to try a file recovery software on the same folder/file. [http://kb.mozillazine.org/Profile_folder Firefox Profile Folder] [http://kb.mozillazine.org/Profile_folder_-_Firefox Firefox Profile Folder & Files] [https://support.mozilla.org/en-US/kb/Recovering%20important%20data%20from%20an%20old%20profile?s=profile&r=1&e=sph&as=s Recovering profile data]

Did you remove personal data when you uninstalled Firefox? In that case you can try to use a utility like Recuva to undelete the cert8.db file that stores the certificates. *http://kb.mozillazine.org/Profile_folder_-_Firefox