First thing, don't close Firefox. Open your profile folder and copy all "sessionstore" files to a safe place. Open your current Firefox settings (AKA Firefox profile) folder using Help > Troubleshooting Information > "Show Folder" button Scroll down and look for files starting with sessionstore. The sessionstore.js file contains the tabs in your current session, so while I recommend saving a copy, it probably won't help you very much. sessionstore.bak contains the tabs from your previous session, which may or may not be useful. If you have files with names like sessionstore-1.js, Firefox created those because there was a problem with updating sessionstore.js and they would be current as of their timestamps. You may also find a file named sessionstore.bak-''datetime'' which is a snapshot of your sessionstore the last time you updated Firefox. Copy all of these to a safe location such as your Documents folder that Firefox will not try to update or clear. Note: If Windows does not show you file extensions such as .js, turn off the hiding so that you can work accurately with files. This article has the steps: [http://support.microsoft.com/kb/865219]. Now... considering the last modified date/time on the files you saved, does any one of them appear to be from the relevant moment so it might contain the missing session? If yes, we can discuss "mining" that file for relevant addresses. If not, hmmm, it might not be possible.