Visit the sites again. The icons should return.

I tried visiting the specific sites again...no luck, still have little empty box.

Do you still see the favicon on the Tab bar if you open such a bookmark in a Firefox tab? Websites that do not have a favicon show an empty square instead in current Firefox versions. You can check for problems with the places.sqlite database file in the Firefox Profile Folder. *http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox *https://support.mozilla.org/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file