Restore the previous session from the Firefox menu Here's how to get back your tabs and windows from a previous session using the Firefox menu: 1. Click on the menu button to open the menu panel. 2. Click History, then Select Restore Previous Session

Restore the previous session every time you open Firefox When Firefox starts, a single window is opened by default, displaying your specified home page. You can set Firefox to always show your windows and tabs from your previous session each time you start Firefox. To change your Firefox startup settings: 1. Click the menu button and select Settings. 2. Select the General panel. 3. Below Startup select Open previous windows and tabs. 4. Close the about:preferences page. Any changes you've made will automatically be saved.

You can try to restore a session from a recent upgrade file in the sessionstore-backups folder in the profile folder.

You will normally find these files in the sessionstore-backups folder:

• previous.jsonlz4 (cleanBackup: copy of sessionstore.jsonlz4 from previous session that was loaded successfully)
• recovery.jsonlz4 (latest version of sessionstore.jsonlz4 written during runtime)
• recovery.baklz4 (previous version of sessionstore.jsonlz4 written during runtime)
• upgrade.jsonlz4-<build_id> (backup created during an upgrade of Firefox)

You can copy a file from the sessionstore-backups folder to the main profile and rename the file to sessionstore.jsonlz4 to replace the current file with Firefox closed.

• make sure to backup the current sessionstore.jsonlz4

You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page (Root directory).

• Help -> More Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data