This is just what I might do, not sure if it's something you'd what to try or not but...

(1) I'd go to my laptop, start Firefox, click "Help", "Troubleshooting Information", "Open Directory"(besides where it says "Profile Directory", once that directory opens, I'd exit Firefox, select ALL the files in that directory, copy them to a thumb drive(possibly zipping them up first).
(2) I'd do almost the same thing on my desktop, going through "Troubleshooting Information" to get to my profile directory(exiting Firefox once I was in the directory), but rather than copying those files, I'd delete them all and replace them with the profile files on my thumb drive.

That's just me though. I do a similar "manual" type sync to my bedroom computer so whatever add-ons, bookmarks, passwords, etc., I have on this computer are also available on my bedroom computer.

Just an idea. Another might be to use Firefox's built-in sync function. I used it for awhile but found it confusing to set up initially, one computer being a master, the other slaves. That might have just been me though. :-)

That is more or less what I was going to say - #1 above - and just copy the whole profile for backup.

But my guess is that somehow the crash created a new profile, and Firefox is automatically using that new profile.
If you're lucky, your original profile is still there, alongside the new one with some similarly cryptic name like "ivnhknrx" under Mozilla\Firefox\Profiles.

If that's actually the case, you just need to tell Firefox to use that profile, and don't really need to back it up, or copy & paste, although backing it up might not be a bad idea. (There are slightly better ways to do that if you're interested, using an extension for that.)

You can change Firefox so that it uses your original profile (again, if it's still there) by using the built-in Profile Manager. But check first using Richard's method to find the profile directory, to see if it's still there.

The first part of this article explains how to run the Profile Manager :
Creating a new Firefox profile on Windows

Here's the same info but written a bit differently :

Use the Profile Manager to create and remove Firefox profiles

Good luck, let us know how it goes.

-Kent

I just lost everything I typed. I'm on my work laptop and found the profile - but had trouble seeing what to copy to my thumb drive. I'll have to open firefox and try again. Not sure I know how to zip files. But I'll highlight, right click and see if I have that option.

If I have the original profile at home, I'd much prefer to ask firefox to use that. (I'll make a copy first - if I can tell which profile is which). How would I do that? what extension?

Thanks.

Lynn.

PS: when I try to click to be notified of responses, it takes me to a page that does not give me a place to choose that. Not sure how to get notified. It used to be automatically set up that way but with Houzz those settings have changed.

Now I'm home. Went to check the Firefox on my desktop. I click help, troubleshooting - but when I click "show folder" nothing appears. (I've done this in the past on this computer - and just did it today on my laptop - so I know what it should look like - but nothing appeared).

Then I thought I'd click "show history." And it said no updates have been installed. So my current version of Firefox does not seem to recognize that I had previous versions of Firefox. I can't imagine how that happened. I've updated 30 or so versions of Firefox and this never happened before. This newest version is 37.0.2.

I also clicked on crash reports and it said no crashes. So the Firefox that crashed yesterday - and it's settings, crash reports, and my profile - has vaporized.

By the way, Richard, when I am on the troubleshooting page, it says Profile Folder, with a blue boxed "show folder." I don't see anything that says "open directory" or "profile directory." Firefox's built-in sync function seemed to be more trouble than it was worth. I looked at it before posting here. Don't recall what I didn't like about it (maybe it forcing more synchronization across computers than I wanted?). But I tried it - and nothing happened. Maybe because I don't have a Firefox profile on this computer at all. I didn't set up FF sync on my laptops. I don't want this "no profile" situation getting synced to the laptops, which are working fine.

Kent - using the second link, I took it to finding Firefox profiles if it can't be accessed through Firefox. I'll try that next. Right now I have to finish a work project tonight before I can resume my troubleshooting.

I'll report back.

Thanks.

Lynn.

Another way to locate your Firefox profile folder...
If you click "Start", "Run", paste in %appdata%\Mozilla\Firefox\Profiles and click "Ok", does a folder open that looks like this?

Thank you, Richard. I used your method and found my Firefox profile. Looks just like your image above. That is my old profile. It's not a new one that Firefox created. I can tell because it includes add-ons, etc, that I had in my previous Firefox, but they are not installed with this latest Firefox 37.0.2.

Rather than copying the profile from my laptop, I'd love to get this profile (that's on my desktop) re-installed. I'm sure "reinstalled" is not the proper term, but I'd like for FF 37.0.2 to use this profile. It is set up exactly the way I want (the laptop one is close, but is missing some important add-ons I had to hunt for and can't seem to recreate on my laptop, as hard as I try). Is there a way to do that?

Thank you.

Lynn.

PS: just looked closer at the Firefox profile. It does have my former content. But it says date modified, May 7, 2015 5:39pm. Yet when I click show folder in Firefox troubleshooting, nothing appears.

And this is the only profile that shows up using start, run and those commands Richard gave me.

Is the profile you found in the correct place ?
If so, just use the Profile Manager as I suggested above - that's what it's for.

You can copy and paste files in, and it might work, but historically that has led to some problems in Firefox. I have done it though.

If you use the Profile Manager, you can be sure Firefox "knows" about a different profile.

Are you having trouble with that ?

(Btw, even if the profile is in an atypical place it will still be loaded by FF and run fine.
I actually put my profiles in a different place that I like to keep them.)

I don't quite understand your reply to me, "I took it to finding Firefox profiles if it can't be accessed through Firefox."

If this clarifies any, you can't run the Profile Manager while Firefox is running. You have to close FF, start the Profile Manager as is explained in the either of the articles, then choose a different profile as the default. It's pretty easy actually.
To start the Profile Manager, in the Start>>Run dialog box, type in: firefox.exe -p

Just reading your latest post which crossed with mine.

Are there normal files in that profile when you use Explorer to go through it ?
If so, I wouldn't worry too much if Firefox's "show folder" button doesn't show what you're expecting right now.
Hopefully the one you found is a useable profile and not corrupted.

And, by the way, you can't use Firefox's "Troubleshooting" page to choose another profile. It's only a presentation of a bunch of xml info that Firefox uses to store settings.

I would make a copy of the profile you want to keep before doing anything, because if something goes wrong, you can at least hope to extract out certain parts of it, like Bookmarks and so on.

If you go "Start", "Run", "firefox -P", "Ok", do you just have one profile listed?

Like this:

Hopefully you'll have a couple listed and can choose the other one.

If that's not the case, I'm afraid I don't know.

Oops, I see my Windows version of Firefox is using different words in "Troubleshooting Information". It's "Show Folder" instead of "Open Directory".

Anyway, if you can get it to show you the profile it's using, you might be able to see what's going on and what you need to do to correct it. Sorry, I'm not a very good explainer.

Edit: I'm so slow Kent beat me to it, better listen to him.

Kent - it worked. Thank you so much. I started profile manager and selected the profile (the default - the only one that was there) - started Firefox back up and all is restored. (I did back up my profile first before I did that).

It's so nice when a fix turns out to be simple.

Thanks again.

Lynn.

And Richard, thank you too. We cross posted so I just saw your response now.

Lynn.

Ok, good to hear !

There is a really good extension for making either complete or partial profile backups, and then to use later to reinstall the complete or partials.

It's named FEBE (Firefox Environment Backup Extension)
You can use it to move a profile to other computers or whatever.
I have it installed, but only enable it when needed.

Here's the developer's page for it :

Firefox Environment Backup Extension

And here it is on FF's extension page :
FEBE extension

I think I remember it can be a little complicated to use if you really get crazy with it.

But just to copy a profile is relatively easy.

And you have a choice : either the profile is backed up as a file, or as the whole set of files, as they are.

Richard, I think you do a great and complete job of explaining.
Hey, we work together on this stuff, right ?

Thank you Kent. I try, but have never did Tech work, except of course fixing my own mess-ups. :-)

" ... I can tell because it includes add-ons, etc, that I had in my previous Firefox ... "
I think that was a good catch/observation Lynn, I think it's good to know your data.

I back up my Firefox profile too. I think because I once had it go corrupt, started getting script errors and reset it. Had to re-add add-ons, do all my little visual tweaks etc. After going through that, I right clicked my firefox folder, choose "Compress"(a Linux thing), and saved a good working copy... just in case. :-)

Now days I keep my profile on a data drive and link to it. I back it up the same way, by compressing/zipping but also through duplication, by copying it to other computers, and the cloud. My Firefox profile from my Linux computer even works fine on my Windows computers.

MozBackup is a great little utility to back up your Firefox settings. I make a new profile every month or so and keep copies several places so all my PC's have the same settings and I never risk losing my stuff. Love it.