Updating to Firefox 43 deleted my tabs.
So I updated to FF 43, and all of my tabs are gone. Some of them were old, trusted friends of mine, and I'd like to have them back.
There's a directory that got created on my desktop that says Old Firefox Data, and there's a sessionstore.bak in there that might have my stuff in it. I closed FF, renamed it to .js and restarted FF, but no luck. Of course, I then realized that I was in aforementioned Old Firefox Data directory, and not the actual Firefox directory.
Navigating to -that- directory, I don't see a sessionstore.js in there at all.
sessionstore-backups -> previous and recovery are the files now.
Check the dates, if you updated from a really old version that folder might not be up to date. Try about:sessionstore in a new url. However if you restarted more that twice it may have been overwritten.
Last resort check your history to restore the tabs that have gone missing. Sorry for the inconvenience.