Hi, you didn't mention the events leading up to the lost tabs, but let me take two guesses: '''(1) Firefox restored your previous session but one or more windows is missing''' First, could you check whether either of these are available (not hidden or grayed out): * "3-bar" menu button > History > Restore Previous Session * (menu bar or Alt+S) History > Restore Previous Session If they are missing or grayed, check either: * "3-bar" menu button > History > Recently Closed Windows * (menu bar or Alt+S) History > Recently Closed Windows Do any of the closed windows have the missing tabs? '''(2) Firefox created a new profile without any of your data''' Please see the steps in the following article: [[Recover user data missing after Firefox update]]. ''If Firefox performed a Refresh/Tune-up or there are some other circumstances, please post a reply with more background on what happened.''