Look through the Firefox directories, but they are probably gone.
From now on do:
1) Install
Pike's Mozilla Firefox Extensions,
2) Install Bookmarkbridge, so you can sync bookmarks between browsers
3) Store a copy on either a cd, flashdrive or online. I store mine in my Yahoo briefcase and on a usbkey. Plus I keep Firefox in sync with Konqueror and Opera.
You can never have too many backups in place.
These are the important files you might want to save:
# bookmarks.html Bookmarks.
# prefs.js Current user preferences.
# user.js User-added preferences (overrides prefs.js every startup).
# cookies.txt Cookies.
# hostperm.1 Cookies permissions, image permissions, and extension website install permissions list.
# signons.txt Saved passwords. Requires the "key3.db" file to work.
# key3.db Supplements password file.
# User.Chrome.css and User.Content.cs
Bookmark Backup can create backups of all of the above files. It has saved me a couple of times when I screwed up my profile.