This might help you: while firefox is running/open type into a new tab about:support and press enter, then press the button that says open profile folder. Keep that folder open and close firefox.
Now while firefox is closed, search your computer for a folder containing an older file (than today's date) for a file called places.sqlite and copy it over to your current profile. You might also want to copy over keys3.db and signons.sqlite and cookies.sqlite. These files contain your history, passwords remembered for sites and cookies.
Remember to first back up the current profile by copying & pasting it into another folder then renaming it before trying to recover info from your old profile. Hope this helps :) xXx