Sorry to hear about this problem. Support forum volunteers would not have suggested an OS reinstall without first making a fresh backup of your Firefox data folders and checking Time Machine for backups you might want to preserve. But we are where we are. Let's see what you have to work with.

(A) Profiles folder

As you may know, Firefox stores your profile data in a hidden folder. This article will help you discover that location:

Profiles - Where Firefox stores your bookmarks, passwords and other user data

Finder may show you a folder with one or more partially random file names, like a34ft7zz.default, or it may show a bunch of files. You want to view the contents of the Profiles folder, so if necessary click up or left a level in Finder.

What folders do you see here? One is your current profile. Any others?

(B) Desktop

Did you use the Refresh feature and end up with an Old Firefox Data folder on your desktop? Was that before or after the problem started?

Thank you. Backups were made. I have 2 folders ending in .default with folders inside including "bookmarkbackups" that contains a folder .jsoniz4. Is it possible that this file could restore my bookmarks? If so, how would I access it?

(B) The problem came out of nowhere and basically took out FF. I got the error message that FF couldn't find my profiles folder, so I spent about 2 hours trying to find it myself (basically trying to guess what could be in it like "bookmarks" and "history"). At one point in trying to restore FF, I did do refresh per the online instructions. It did nothing whatsoever to locate the folder--just the opposite--I got the feeling I just wiped it out.

Automatic bookmark backups in bookmarkbackps should have the creation date (also the number of bookmarks+folders) coded into the file name. Are they recent enough that you want to try restoring one of them? Restoring is a complete replacement of your current set of bookmarks. If you have any new bookmarks you need to preserve, create an Export file first.

These articles have the steps:

• Export Firefox bookmarks to an HTML file to back up or transfer bookmarks
• Restore bookmarks from backup or move them to another computer -- there's a Choose File option at the bottom of the Restore menu to point Firefox to wherever you found the backup files.

I'm puzzled that Firefox couldn't start because it couldn't find your profile, yet you were able to run a Refresh. ?? Usually the missing profile error completely prevents running Firefox, and you need to use the steps in this article: How to run Firefox when your profile is missing or inaccessible.

Yes, it has the creation date. I created an html file, went to the FF library, went to Restore and attempted to choose the file and it won't let me. Then I tried going to Import html and chose the html file and it allows it, click Open and nothing.

What am I doing wrong?

For Restore, you need to select the .jsonlz4 file you found earlier. The purpose of creating the HTML export was to create a copy of what you have now because the Restore will overwrite it.

What a waste of time! No more. I tried about 10 files in the FF data that was saved and nothing did anything whatsoever, yet every file said it was going to replace all my current bookmarks with the backup. Strange how all the files were all bookmark files--even the faviconsqlite file and others gave me the same mssg. There. I wish I had never gotten FF. I know now.

I even searched through old data on an external hard drive with a copy of FF--nothing--all the same. There is no backup. Never was, apparently.

Did the backup file names indicate a date and number of items that would appear to match what you were expecting? For example, this one has 6,376 items from May 8, 2019:

bookmarks-2019-05-08_6376_gibberish==.jsonlz4

On your backup hard drive, is the folder still hidden? As a Windows person, I can only point you to steps suggested by others to find the folder, I can't test myself.

https://www.google.com/search?q=access+hidden+library+folder+on+external+drive

You can use this tool to inspect compressed .jsonlz4 backups.

• https://www.jeffersonscher.com/res/bookbackreader.html

You can check for problems with the places.sqlite and favicons.sqlite files in the Firefox profile folder.

• use "Verify Integrity" button on the "Help -> Troubleshooting Information" (about:support) page

In case errors are reported with "Verify Integrity" close and restart Firefox and retry.

If "Verify Integrity" cannot repair places.sqlite then remove all places.sqlite and favicons.sqlite files in the Firefox profile folder. Firefox will rebuild places.sqlite and restore the bookmarks from a recent JSON backup in the bookmarkbackups folder.

• keep a backup copy of places.sqlite in case a new places.sqlite database has to be created

See also:

• https://support.mozilla.org/en-US/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file
• https://support.mozilla.org/en-US/kb/fix-bookmarks-and-history-will-not-be-functional

This is the name: 2019-05-09_11_ev3MA31DiQl9L37QBzHYnA==.jsonlz4. I would expect it to contain 1000+ bookmarks.

Re Convert/Repair/Whatever--I pasted the required data into the box and asked it to check it. It says "Done". Was it supposed to do something.

I'm afraid that Verify Integrity is just another game to waste my time.

Thanks for trying to help.

This indicates 11 items:

2019-05-09_11_gibberish==.jsonlz4

So that is not going to be useful.

But you said the crash was over the weekend, so you need to find a file with a date before that, such as 2019-05-03 or 2019-05-04.