Were you using the Session Manager extension before?

When you use the Refresh feature, your entire old settings folder is moved to your desktop inside an Old Firefox Data folder. Because each add-on stores its data differently, I really do not know the correct steps to move Session Manager data to your currently active settings folder (AKA your profile folder). There might be steps or support available from the extension author on that.

There might be an import feature in the Session Manager settings, so you can check that. You need to check the content of the "Old Firefox Data" folder on the desktop to see if you can locate the backups.

If SM doesn't have an import feature then you need to copy the content of the SM backup folder to the current Firefox profile folder.

You can use this button to go to the currently used Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox