If you check these menu commands, are either of them available at startup: * "3-bar" menu button > Restore Previous Session * (menu bar) History > Restore Previous Session If they are grayed, check either: * "Library" toolbar button > History > Recently Closed Windows (and within each restored window, Recently Closed Tabs) * (menu bar) History > Recently Closed Windows (and within each restored window, Recently Closed Tabs) If there's nothing there either: Make sure Firefox is set to record and retain session history. You need to avoid automatic private browsing and avoid clearing history when Firefox closes. You can check that here: * 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 * Any system: type or paste '''about:preferences''' into the address bar and press Enter/Return to load it In the left column, click Privacy & Security. On the right side, the History selector can have one of three values: * Firefox will: Remember history -- you're good * Firefox will: Never remember history -- NOT compatible with restoring previous sessions * Firefox will: Use custom settings for history -- check the details: ** "Always use private browsing mode" NOT selected ** "Remember my browsing and download history" IS selected ** "Clear history when Firefox closes" NOT selected --or-- if this is selected, click the "Settings" button to the right and make sure that you are not clearing "Browsing and download history"