I don't know what caused this. I manually restarted Firefox and noticed in the Task Manager that Firefox's process was not ending. It does this from time to time, so I took a little break from the computer assuming that it would end in a minute or so. After a couple of minutes from the computer, I saw that Firefox's process was still running. Instead of manually ending the process, I reopened Firefox just because. And usually when you reopen while the process tries to end, a prompt comes up on the screen telling you that Firefox is still running and you should wait for it to close, but that did not happen. Instead, Firefox reopened while the process was still running from the last time. And when Firefox opened again, I didn't have any of my app tabs and all of my open tabs and tab groups from before were gone. So I tried checking the history tab for recently closed stuff and my old window with my app tabs, etc. was saved so I opened that and closed the window without my stuff thinking all would be well. But then I restarted Firefox again to assure that the process would close and it did, but when I reopened Firefox, my app tabs and opened tabs and tab groups were gone again but the recently closed windows menu was grayed out. So now all of my stuff is gone and I don't know how I can get it back or what specifically caused this to happen. It's really frustrating, especially considering that I don't have the box checked for Firefox to clear history when I close it, and I do have the box checked for Firefox to remember my browsing and download history. What can I do, if anything, to bring back my stuff? I tried restoring my history with FEBE, but it just keeps freezing up Firefox and isn't helping at all. Someone please help me.