Many but not all Favicons disappeared from my tabs & bookmarks last week - how can I get them back?

Question

I have been using many of these for years, eg google and tvguide.co.uk but now they show as dot edged boxes instead of favicons on tabs. Others are OK eg Firefox and Facebook. All these sites still display correctly in other browsers.
I have: cleared history, cookies and cache / deleted and remade bookmarks / tried safe mode / restarted several times / tried some recovery addons, but nothing works.
I updated to FF 25 at about the time I noticed this problem and am running Windows 8

Answer 1

Do you see the favicon on the tab if you visit one of those sites?
Normally Firefox should fetch the favicon from the server if you click a bookmark to visit this link.
You can check these prefs on the <b>about:config</b> page to make sure that they have the default value.
*browser.chrome.favicons
*browser.chrome.site_icons
Try to let all favicons expire to see if that makes Firefox to store properly them once again.
Copy and Paste the JavaScript code in the command line in the Browser Console (Firefox/Tools > Web <pre><nowiki>Developer;Ctrl+Shift+J) and press the Enter key.
var fS = Components.classes["@mozilla.org/browser/favicon-service;1"]
.getService(Components.interfaces.nsIFaviconService);
fS.expireAllFavicons();</nowiki></pre>
(note that this will remove all favicons, so you need to open a bookmark to make Firefox retrieve the favicon)
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
Note that your System Details List shows that you have a user.js file in the profile folder to initialize some prefs on each start of Firefox.
The user.js file is only present if you or other software has created it, so normally it wouldn't be there.
you can check its content with a plain text editor if you didn't create this file yourself.
The user.js file is read each time you start Firefox and initializes preferences to the value specified in this file, so preferences set via user.js can only be changed temporarily for the current session.
You can delete the prefs.js file and possible numbered prefs-##.js and user.js files to reset all prefs to the default value or reset these prefs to the default value via the right-click context menu on the <b>about:config</b> page or edit the prefs.js file and remove related line(s).
*http://kb.mozillazine.org/Preferences_not_saved