Sorry to hear about that. If you haven't already, before doing any file moves/deletes/reinstalls, you may want to do a normal system shutdown and startup to release any file locks and complete any pending updates. One user reported it took three shutdown/restarts to sort out his issues.

If your data does not magically reappear, the most likely scenarios for complete data loss are:

(1) A Refresh started but the migration of data from your old profile to your new profile was incomplete, or
(2) Your old profile was locked, so Firefox ignored it and created a new one.

Here's how to investigate those two possibilities:

Did Firefox perform a Refresh?

Unless it was interrupted in progress, you should find a folder on your desktop named Old Firefox Data. Inside would be a semi-randomly-named folder with freshly updated files. Do you see anything like that?

If so, we'll suggest how to rescue key files or completely restore the earlier profile folder.

If not...

Does the Profile Manager list your immediately previous profile folder?

To check on that, inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

This page should list all the profiles Firefox is currently aware of. If you see a profile that is not currently set as default that looks promising, scroll down to it and click the Set as default profile button below that profile, then scroll back up and click the Restart normally button. (There are some other buttons, but I think those are still "under construction" so please ignore them.)

Firefox should exit and then start up using the other profile. Is that the right one?

If it's not there...

Did Firefox orphan your old profile folder?

Here's how to check whether there are additional profile folders in the standard location in addition to the one you're using. Start by opening your current 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/Return

In the first table on the page, click:

* Windows: the "Open Folder" button, to launch a new window listing various files and folders in Windows Explorer.
* Mac: the "Show in Finder" button, to launch a new window listing various files and folders in Finder.

In the Windows Explorer address bar, click the capitalized word Profiles to move up one level in the folder hierarchy. More than one folder here by any chance? Do the files in those folders look like they were last updated around the time of the update?

(Mac users: please do what you need to do in Finder to check up one level...)

If you've got any promising looking folders, we can discuss next steps to recover use of them.

1) No folder on my desktop named Old Firefox Data

2) There is only one profile listed under the profile manager

3) There is only one profile folder showing

It looks like everything is just gone. I didn't realize that I should back those settings up somewhere as I thought that firefox backed up so many days.

In the future, you may want to include Firefox's profile folders in the same backup plan you use for documents, media, etc., bearing in mind that all your history is in there, so... it's a bit personal.

Are there any other Windows users set up on your system? It may be helpful to set Windows to show hidden files and folder before exploring:

https://support.microsoft.com/en-us/help/14201/windows-show-hidden-files

Then check under:

C:\Users\other-user-names\AppData\Roaming\Mozilla\Firefox\Profiles

Also, there's a possibility that Windows captured a snapshot of your Firefox profile folder in a restore point. I do NOT recommend using system restore, but you can use a third party utility to check inside a recent restore point for a bookmark backup file and copy it out.

http://nicbedford.co.uk/software/systemrestoreexplorer/

Within the restore point, explore to:

C:\Users\your-user-name\AppData\Roaming\Mozilla\Firefox\Profiles

Try to find a folder named bookmarkbackups containing compressed files that have their creation date coded into the name. Save one or two promising candidates to your Desktop or Documents folder for easy access. Then this article has the steps to replace your current set of bookmarks with the contents of the backup file:

Restore bookmarks from backup or move them to another computer

I have no idea what is going on with my firefox. Everytime my computer reboots it loses everything and is like it is newly installed.

I have even uninstalled and reinstalled firefox. My computer is clean and shows no viruses or spyware. I've tried everything. I guess I just have to give up using firefox and use a different browser. I'm not having issues with anything else on my computer and my other browsers are fine.

I used the software to look at the files in my system restore and I found my profile from 7/18 and it has the bookmarks. I copied them to my desktop and then tried to import them into firefox but I get a message that says it is not able to process the file.

If you have the file with a name following this pattern

bookmarks-2017-07-26_3456_-gibberish==.jsonlz4

you should be able to "Restore" it with the steps in this article: Restore bookmarks from backup or move them to another computer. Is that the process that failed?