Hi Christine, sorry to hear about this problem.

Did the updater mention needing to do a Refresh, Reset, or Tune-up, or creating a new profile?

If not, try the steps in the first section of the following article: Recover lost or missing Bookmarks

In the past whenever I did an update, it usually was from a pop-up that would download in the background—however, this time I updated from a download link in an email from Mozilla. The install failed so I closed my open tabs in an attempt a restart. Turns out, the Firefox app was already deleted by the incomplete install so I initiated a second download. After reinstalling Firefox for a second time, my tabs were missing while the history and bookmarks were there but I was concerned about all my tabs being lost. I had hundreds of open Firefox tabs on a dozen or more separate Firefox sessions. I closed and reopened Firefox again and it asked if I wanted to restore my history, but now it only showed the tabs from the new install, not the old files. I would like to have all my tabs back. There is a file called Old Firefox Data on my desktop, but all the folders appear to be empty. Is there anything else you can suggest to help find and restore my old tabs, history, and bookmarks? Thank you so much for your assistance!

Hi Christine, I don't how far back we can recover. As a first step, if you reopen the items on the following list, are any of your old tabs there:

menu button > History > Recently Closed Windows

If not, did you check for other available profiles as mentioned in the first section of this article:

Recover lost or missing Bookmarks