hello, could you go to the firefox menu ≡ > help ? > troubleshooting information, copy the contents of that page and paste them here into a reply on the forum? this might give us a clue what is going on...

Make sure that you close Firefox with all windows still open and not have the menu bar visible with all windows closed.

Did you check for History > Recently Closed Tabs/Windows?

Make sure that you do not run Firefox in permanent Private Browsing mode (Never remember history).

• https://support.mozilla.org/kb/Private+Browsing

• Firefox > Preferences > Privacy > Firefox will: "Use custom settings for history"
• Deselect: [ ] "Always use Private Browsing mode"

In case you use "Clear history when Firefox closes":

• do not clear the Browsing History

• Firefox > Preferences > Privacy > Firefox will: "Use custom settings for history": [X] "Clear history when Firefox closes" > Settings
• https://support.mozilla.org/kb/remove-recent-browsing-search-and-download-history

I still have this issue. what I've been doing is not closing out firefox. when my computer restarted, it would restart firefox because my settings were set to restart of unclosed programs etc. I recently closed firefox, restarted my computer and i've lost my previous opened tabs.

here is the text your requested:

Give Firefox a tune up Try Safe Mode Troubleshooting Information This page contains technical information that might be useful when you're trying to solve a problem. If you are looking for answers to common questions about Firefox, check out our support website. Application Basics Name Firefox Version 38.0.1 Build ID 20150513174244 Update History Update Channel release User Agent Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:38.0) Gecko/20100101 Firefox/38.0 Profile Folder Enabled Plugins about:plugins Build Configuration about:buildconfig Memory Use about:memory Multiprocess Windows 0/1 (default: false) Crash Reports for the Last 3 Days Report ID Submitted bp-9d0b800a-a153-49e0-b9ae-a6ac22150525 2 days ago

All Crash Reports Extensions Name Version Enabled ID Pin It Button 1.35 true jid1-YcMV6ngYmQRA2w@jetpack Graphics Device ID 0x a26 GPU Accelerated Windows 1/1 OpenGL (OMTC) Vendor ID 0x8086 WebGL Renderer Intel Inc. -- Intel HD Graphics 5000 OpenGL Engine windowLayerManagerRemote true AzureCanvasBackend quartz AzureContentBackend quartz AzureFallbackCanvasBackend none AzureSkiaAccelerated 0 Important Modified Preferences Name Value accessibility.typeaheadfind true accessibility.typeaheadfind.flashBar 0 browser.cache.disk.capacity 358400 browser.cache.disk.smart_size.first_run false browser.cache.disk.smart_size.use_old_max false browser.cache.frecency_experiment 2 browser.download.importedFromSqlite true browser.places.smartBookmarksVersion 7 browser.sessionstore.upgradeBackup.latestBuildID 20150513174244 browser.startup.homepage google.com browser.startup.homepage_override.buildID 20150513174244 browser.startup.homepage_override.mstone 38.0.1 browser.tabs.warnOnClose false dom.mozApps.used true extensions.lastAppVersion 38.0.1 font.internaluseonly.changed false font.language.group x-western media.gmp-gmpopenh264.lastUpdate 1432072701 media.gmp-gmpopenh264.version 1.4 media.gmp-manager.buildID 20150513174244 media.gmp-manager.lastCheck 1432737218 network.cookie.prefsMigrated true network.predictor.cleaned-up true places.database.lastMaintenance 1432682749 places.history.expiration.transient_current_max_pages 104858 plugin.disable_full_page_plugin_for_types application/pdf plugin.importedState true print.print_bgcolor false print.print_bgimages false print.print_colorspace print.print_command print.print_downloadfonts false print.print_duplex 1515870810 print.print_evenpages true print.print_in_color true print.print_margin_bottom 0.5 print.print_margin_left 0.5 print.print_margin_right 0.5 print.print_margin_top 0.5 print.print_oddpages true print.print_orientation 0 print.print_page_delay 50 print.print_paper_data 0 print.print_paper_height 11.00 print.print_paper_name print.print_paper_size_type 1 print.print_paper_size_unit 0 print.print_paper_width 8.50 print.print_plex_name print.print_resolution 1515870810 print.print_resolution_name print.print_reversed false print.print_scaling 1.00 print.print_shrink_to_fit true print.print_to_file false print.print_unwriteable_margin_bottom 56 print.print_unwriteable_margin_left 25 print.print_unwriteable_margin_right 25 print.print_unwriteable_margin_top 25 privacy.sanitize.migrateFx3Prefs true storage.vacuum.last.index 0 storage.vacuum.last.places.sqlite 1432598407 Important Locked Preferences Name Value JavaScript Incremental GC true Accessibility Activated false Prevent Accessibility 0 Library Versions Expected minimum version Version in use NSPR 4.10.8 4.10.8 NSS 3.18.1 Basic ECC 3.18.1 Basic ECC NSSSMIME 3.18.1 Basic ECC 3.18.1 Basic ECC NSSSSL 3.18.1 Basic ECC 3.18.1 Basic ECC NSSUTIL 3.18.1 3.18.1 Experimental Features Name ID Description Active End Date Homepage

leighbydesign said

i have my settings set so that the previous sessions should be shown to me when i reopen firefox. this worked fine for awhile but then it just stopped. i would like this fixed please.

in your address bar type about:support hit enter look in the upper right hand corner click on refresh firefox then shut firefox down and restart then select the option you want.

this worked for me