Binabik: Are you on Windows? If you open the folder C:\Documents and Settings\YOUR_WINDOWS_NAME_HERE\Application Data\Mozilla\Firefox\Profiles\ (or some such) how many folders do you get? Should be 1! If there's more than 1 folder you may be able to fetch your bookmarks from a "old" folder to the most recent one.
Close Firefox before moving files within these folders.
(hide) In the mood for a quick game that is guaranteed to finish within 2 hours? Create a new game of your preference, select the Time for game and set Time to 0 days / 1 hour, Bonus to 0 days / 0 hours and Limit to 0 days / 1 hours. (TeamBundy) (show all tips)