Did your computer restart during that time? Occasionally users report that after Windows updates and a restart, Firefox does not get full permissions to its settings and/or Windows start up in the wrong user account.

Assuming you can rule that out:

Did Firefox start up in a new profile? To check for other profiles, try this:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Show Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Make a brief note of the semi-random profile name in the address bar, then click the word "Profiles" to navigate up one level. Are there any other profile folders here?

Upon closer reading, could you check your desktop for an Old Firefox Data folder? If Firefox's Refresh feature ran, there would be a freshly updated, semi-randomly-named profile folder inside.

There's no "undo" for a Refresh, but there is a multi-step manual roll back process you could try...

Check inside the "Old Firefox Data" folder that Refresh adds to your desktop for a folder with a semi-randomized name. If there's only one, that probably has your old settings and add-ons. If there's more than one, you'll want to work with the one that was updated most recently.

Once you have identified the profile folder you want to restore, here is my suggested "old profile resurrection procedure":

Overview

These are the steps described in more detail below:

1. Create a new Firefox profile (Firefox 47+)
2. Remove everything from that new profile folder
3. Copy in everything from the old profile folder

Create a new Firefox profile (Windows)

In Firefox, type or paste about:profiles in the address bar and press Enter/Return to load that page.

Click the "Create New Profile" button and assign a name like OldSettings. Ignore the button for changing the folder location and click Finish.

Next, scroll down and below the Profile: OldSettings box, click the "Set as default profile" button.

Then scroll back to the top of the page and click the "Restart normally" button. This should exit Firefox and start Firefox up in that new profile.

Open the New Profile folder in Windows Explorer

Firefox in the new profile should look like a factory fresh installation. Open the Troubleshooting Information page using either:

• "3-bar" menu button > "?" button > Troubleshooting Information
• Help menu > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table, click the "Show Folder" button. Firefox will launch your brand new profile folder in Windows Explorer.

Leaving that folder open, switch back to Firefox, and Exit using either:

• "3-bar" menu button > "power" button
• (menu bar) File > Exit

When Firefox closes, the profile folder should be front and center, or you can activate it using the Task bar.

Copy Old Data in Place of New

In that new profile folder you just popped open -- NOT the one on your desktop -- select all the contents (you can use Ctrl+a) and delete (you can press the Delete key on the keyboard).

Leaving that window open, open or switch over to your Old Firefox Data folder. Drill down into your old profile folder. At this level you should see a folder named bookmarkbackups among many other things.

Select everything (Ctrl+a) and Copy (either right-click > Copy or Ctrl+c).

Switch to the empty new profile folder in other window and Paste (either right-click > Paste or Ctrl+v). This may take a minute since some of the files are large.

Start Firefox

Firefox should start up in that "new" profile with the resurrected old profile data. Success?

jscher2000 said

Did your computer restart during that time? Occasionally users report that after Windows updates and a restart, Firefox does not get full permissions to its settings and/or Windows start up in the wrong user account. Assuming you can rule that out: Did Firefox start up in a new profile? To check for other profiles, try this: Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Show Folder" button. This should launch a new window listing various files and folders in Windows Explorer. Make a brief note of the semi-random profile name in the address bar, then click the word "Profiles" to navigate up one level. Are there any other profile folders here?

Yes, the on file name is: t5yweag2.default Done today @ 7/7/16 @ 3:57pm (I saw you earlier helped a guy that was in Win 10 and lost his tabs. You told him to rename or delete his 'sessionstore' files, I did not delete my files, i just renamed them and did the rest and nothing happened, so I'm here now).

I'm sorry, did you find any additional profile folders? The two places you might find additional profile folders are:

(1) The Profiles folder that contains your currently active profile folder (2) An Old Firefox Data folder on your desktop

Regarding lost tabs, is that the issue you have? I'm unclear on what exactly you lost and what you didn't lose.

Also there is on desktop an Old Firefox Data folder which contains 2 files and the latest one is: 'nragh1tj.default-1384206833438' for 6/6/16 @ 1:48pm, which do I use?

So remind me what data you want to restore?

If you look inside the various additional profile folders, which has the most recently updated prefs.js file? Most of the settings you change in Firefox (on the Options page, on about:config) are stored in that file.

Note: By default, Windows hides the .js extension. To ensure that you are looking at the files I mention, you may want to turn off that feature. This article has the steps: http://windows.microsoft.com/en-us/windows/show-hide-file-name-extensions

No, I didn't have any "lost tabs", that was just the closest questions/answers I saw to my problem before I actually put my "Win 7 lost personal settings" problem issue out on the support forum. Anyway so I presently have (per your instructions) in the 'profiles folder: t5yweag2.default (done today 7/7/2016 @ 3:57pm & I also have on my desktop an Old Firefox Data folder which contains 2 files, the latest one of those two is: nragh1tj.default-1384206833438' done on 6/6/2016 @ 1:48pm; which file do I use? (I'm cautious because I had to take my computer in last time this happened.

OK, I found latest prefs.js done on 7/7/2016 @ 3:09pm

I suspect 3:09pm might be your current prefs.js file, which doesn't really help you recover old settings.

If your settings do not change frequently, you could try using the prefs.js file from your June 6th profile. The procedures to swap would be the familiar:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Show Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > "power" button
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup, then rename prefs.js to something like prefs-old.js.

Copy the prefs.js file from your June profile folder into your current one.

Start Firefox back up again and the applicable settings from June should be in effect.

By the way, does your current profile folder have any numbered prefs files, like prefs-1.js? These are created if Firefox can't update prefs.js.

You also could check for an intermediate version of prefs.js using the Versions tab:

right-click your current prefs.js file, choose Properties, then select the Versions tab. Windows should check restore points for earlier copies of the file. Please do any restoration to a different location for safekeeping and then swap in the file using the steps described earlier.

You know what, this is impossible!!!!!! NOW even my settings that were stored still on my bookmarks are COMPLETELY GONE!!!!! You guys going to tell my customers what happened?!

I did what your instructions stated and now the only jscript script I can find is for a later time of 7/7/2016 @ 5:45pm & the FF browser opened with NOTHING AT ALL!!!!!!!!! What the %^%$%^&*(&%$!

jscher2000 said

By the way, does your current profile folder have any numbered prefs files, like prefs-1.js? These are created if Firefox can't update prefs.js. You also could check for an intermediate version of prefs.js using the Versions tab: right-click your current prefs.js file, choose Properties, then select the Versions tab. Windows should check restore points for earlier copies of the file. Please do any restoration to a different location for safekeeping and then swap in the file using the steps described earlier.

That Old desktop file dated 6/616 has the pref.js file dated 4/8/2015 & I have the other pref.js file dated 7/7/2016 @ 5:47pm, In the properties box - there is NO previous versions!!!! This is all I have left, so just tell me how to get my latest settings back and I'll do it by hand!!!!!!!!!!!! I told you at begining I could have done this manually, but I get tired of FF removing my setting & then I have to do it manually! Just get me to recover latest 7/7/2016 jscript info!

The prefs.js file has nothing to do with bookmarks. Your Firefox settings are unstable for some reason.

Undo the prefs.js change to roll back to your settings file from earlier this afternoon:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Show Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > "power" button
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup, then rename prefs.js to something like prefs-bad.js.

Rename the prefs-old.js file back to prefs.js.

Start Firefox back up again and the applicable settings from earlier this afternoon should be in effect.