Have you ever had a Firefox extension just stop working? I’m not talking about an extension not working properly after being updated, an extension that worked properly with one version of Firefox but doesn’t work after Firefox is updated, an extension that fails installation altogether, or an extension with some odd reproducible problem. I’m talking about an extension that worked properly for months, and then suddenly stops working without Firefox or the extension itself being updated. Say you’ve been using AdBlockPlus for ages, and one day you notice that ads are no longer being blocked and the AdBlock icon is missing from the toolbar and\or status bar. Neither Firefox nor AdBlock have been updated… it just no longer works!
It’s possible that the extension itself has become corrupted, but it’s more likely that Firefox’s extension database has become corrupted Here’s one quick and easy thing to try that just might fix this:
1) Make sure that Firefox is closed.
2) Click Start > Run and type the following into the “Run:” text box. Press ENTER when done:
%appdata%\Mozilla\Firefox\Profiles
3) Click on your profile folder (it will have an odd name, such as “49g0xduq.default”).
4) Delete the following files: extensions.ini, extensions.cache and extensions.rdf.
5) Restart Firefox.
Firefox will rebuild those three files the next time your restart the browser. If this does not fix your problem, try uninstalling and reinstalling the extension.