Comment 8 for bug 309656

I have a recovery process for you, but it requires that you have immediately saved your old sessionstore.bak, or have a way to get one from your company backup system.

cd .mozilla/firefox/<your current profile>/

<your current profile> will probably have a name like 'wzy9plsu.default'. If there are more than one check the dates.

you should find that you have a file named sessionstore.bak. Immediately save a copy of it

cp -a sessionstore.bak sessionstore.bak2

Now start up firefox. Create a new tab. Exit firefox and tell it to save tabs. Then overwrite the
file firefox just created:

cp -a sessionstore.bak2 sessionstore.js

restart firefox and if you had the correct backup file, your sesions should be back.

My guess is there is a flag somewhere else that says to firefox that it has a 'virgin' install, and until you cause that to get cleared, it will not pay attention to old contents of sessionstore.js or use the usual sessionstore.bak.

Hope this saves a few people some grief.