Try closing Firefox ( Firefox menu -> Exit) and then reopen it. Is the Add-ons Manager about:addons page Extensions list still empty? If so,

Does the problem happen when you restart in Firefox Use Troubleshoot Mode in Firefox and select "Continue in Safe Mode? If you can see the Extensions list from Safe Mode you may have another add-on that is causing the problem. See the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for more information.

If the Add-ons Manager Extensions list is still blank in Firefox Use Troubleshoot Mode in Firefox then the problem could be corrupt extensions.* files in your Firefox profile folder. Open the Help -> Troubleshooting Information page, click on "Open containing folder". A Windows will open showing the contents of the Firefox profile folder. Close all Firefox browser windows first, then delete or rename any of these extensions.xxx files you find in the profile folder window (e.g., rename extensions.sqlite to extensions.sqliteOLD)

• extensions.sqlite
• extensions.sqlite-journal
• extensions.ini
• extensions.cache
• extensions.rdf

Ref.:

• /questions/671201
• /questions/751390
• http://kb.mozillazine.org/Unable_to_install_themes_or_extensions#Corrupt_extension_files

Hi Alice love,

I have never used Safe Mode before, I am not sure what to do.

Sorry for being a pest love

Al

The Use Troubleshoot Mode in Firefox article explains how to start in Firefox Safe Mode (which is different from Windows Safe Mode):

How to start Firefox in Safe Mode

At the top of the Firefox window, click the Firefox button, go over to the Help menu and select "Restart with Add-ons Disabled".... Firefox will start up with the Firefox Safe Mode dialog.

Note: You can also start Firefox in Safe Mode by holding down the shift key while starting Firefox.

When the Firefox Safe Mode window opens (SCREENSHOT), click "Continue in Safe Mode".

Hello Alice love,

I started Firefox in Safe Mode, then I opened the Add-ons Manager. When I clicked on the Plugins, they were all there. But when I clicked on Extensions, the box was still empty.

Al

Hi, Al.

In that case, try my second suggestion, above (delete or rename the extensions.xxx files in the Firefox profile folder for example: rename extensions.sqlite to extensions.sqliteOLD, etc.)

Hello Alice love,

I done what you said and it worked fine thank you Alice love, I had to enable them one at a time and deleted a couple that were not compatable with Firefox 10. But things are working just fine now thank you very much Alice love, I could kiss you but the USA is a bit far from Scotland sorry love. :-))

Thank you agian Alice love.

Take care.

Love

Al XXXXX XXXXX

So, my second suggestion, deleting or renaming extensions.sqlite, extensions.ini, etc., fixed it? Great! I marked that as the solution.

Hello Alice love,

Yes, it was very helpful Alice love, Now I understand a bit more about Firefox thanks to you love.

Thank you Alice love.

Al XXXXX