Hi Blaz, Firefox probably would have stored the certificate in a file named '''cert8.db''' in your active Firefox profile folder on the old drive. This is under a hidden path, so the first step is: http://windows.microsoft.com/en-us/windows/show-hidden-files And .db may be a hidden file extension, so: https://www.bleepingcomputer.com/tutorials/how-to-show-file-extensions-in-windows/ Next, try to drill down here (assuming your old drive is "E"): E:\Users\''username''\AppData\Mozilla\Firefox\Profiles In that folder, you might find one or multiple semi-randomly-named folders. Whichever one was updated last probably was your active profile folder. You can copy the latest cert8.db file to your desktop (or if you are using a USB flash drive, that device). To replace a file in your currently live Firefox profile folder: Open your profile folder using either * "3-bar" menu button > "?" button > Troubleshooting Information * (menu bar) Help > Troubleshooting Information * type or paste about:support in the address bar and press Enter In the first table on the page, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows Explorer. Leaving that window open, switch back to Firefox and Exit, either: * "3-bar" menu button > "power" button * (menu bar) File > Exit Pause while Firefox finishes its cleanup, then rename '''cert8.db''' to something like cert8-old.db. Then copy/paste the file from the desktop (or USB flash drive) into this folder. Start Firefox back up again. Is your personal certificate present? You can check using the Options page: * Windows: "3-bar" menu button (or Tools menu) > Options * Mac: "3-bar" menu button (or Firefox menu) > Preferences * Linux: "3-bar" menu button (or Edit menu) > Preferences In the left column, click Advanced. Then on the right side, with the "Certificates" mini-tab active, click the "View Certificates" button. It would be in the "Your Certificates" category. Success?