Reversing "Restart Firefox to its default state"
I started Firefox in its default state and lost all my bookmarks, history and toolbars. I now have a shortcut on my desktop named Old Firefox Data. How do I reverse this action? I, especially, would like to retrieve my Bookmarks and Toolbars. The blurb did not warn me that this action may be irreversible. <sigh>
Opaite Mbohovái (1)
While Firefox is closed, copy the places.sqlite file into your new profile folder. This should restore your bookmarks and history.
Add-ons that provide toolbars must be reinstalled. Since add-ons are a common source of problems, it would best to first verify the issue you were trying to solve is gone.
I don't recommend restoring your old interface customization file (localstore.rdf). It could contain references to buttons provided by add-ons that are no longer installed, which could cause problems.
That's "reset", not "restart". It's a feature that tries to keep your essential data like bookmarks and passwords, but discards add-ons and other stuff that could be the source of problems. On the other hand, Safe Mode is temporary ("Restart Firefox with add-ons disabled"). You can also manually start in a brand new profile, then switch back to your old one.