[DATA LOSS] I closed the Tab Groups and all my tabs dissapeared. How can I recover the tabs in Firefox 26? Would you please just delete this feature?

Question

Thank-you in advance for reading all of this.
A slip of the mouse in trying to return to the left-most tab caused the tab groups feature to take over the window. I completely failed to comprehend what I was looking at and closed the thing by clicking the x because I damn sure didn't want what I was looking at. Undo close group? Of course not, I didn't want a group in the first place. Hey! My tabs are completely gone now! So in just a few steps all of which seemed innocent, I have lost all but ten of the tabs that were open, and those were only the most recent ten (and actually older tabs would have been more valueable than newer so insult on top of injury).
I don't think increasing the number of undoable tab closures is the answer. I think getting rid of the tab groups feature all together is the best way to go. I seem to have lost all the tabs I had open, irretrievably, and some of them had been open for WEEKS so they can't be reopened from history.
The tab groups feature is a data loss bug. Please remove it from the UX completely. If you have to figure out a way to grandfather people who actually have a tab group, fine but don't further vex me with it, please.
The reason this catastrophe has occurred is that your feature, was so discoverable that I activated it by mistake, and the UI after that had to be learned on the spot, yet was too complicated to learn. You really should withdraw it until you can figure out how to keep the UI for it from causing data loss such as I have experienced this morning.
Also, there may be other questions on this feature which are from a certain point of view the same as this one. It's hard for me to tell for sure. None of them had a true resolution so that's why I posted this one, also I'm seeking a specific fix, removal of the offending feature.
Why remove the feature? Because if I allow in my discussion the possibility of retaining it, it will stick around in its present and dangerous form until your team is done bikeshedding the new form it should take. Instead I want you to delete the feature and then require its champion to convince you that a new incarnation won't cause data loss before you allow it back in.
Fellow users, if you know of a way to recover all 50 lost tabs from an "undo close tab group incident", I would be grateful for that advice, but I would still believe the feature should be deleted. Some of the tabs have been retained for months so digging them out of the history is not practical.

Answer 1

I am not 100% certain but I am fairly sure development of this tab feature has ceased and it is likely to be deprecated. I am even less sure what the replacement will be.
Thus forum is not the place for discussing development issues or feature requests. (Developers do not use this site)
*You could comment using feedback <br /> https://input.mozilla.org/en-US/feedback
*Or try to find a developers forum or mailing list <br /> http://www.mozilla.org/about/forums/#general-development
I have not tried this and am not even using Windows at present but the tabs groups are stored as entries in the sessionstore.js files. Firefox has such a file plus sometimes numbered copies and a backup copy. Firefox will have re-writen these files but I suppose there is a posibility the Windows OS may have kept copies.
* see http://windows.microsoft.com/en-US/windows7/Previous-versions-of-files-frequently-asked-questions
* http://kb.mozillazine.org/Sessionstore.js Note the files are kept within the Firefox Profile
** Firefox Button -> Help -> Troubleshooting [open profile] (or some thing similar) is one method of locating the profile.
Find and backup any current sessionstore.js file. Consider also bookmark or otherwise recording anything you have open. Now find any previous versions and try putting them in Firefox's profile before restarting it.