Perhaps you can provide more information about the change you see, and what version of firefox you are comparing this with.

You have plugins listed aside in your system info, are you able to see those by using

• Firefox Button -> Add-ons -> | plugins|

You should be able to discover your Add-ons in a similar manner

• Firefox Button -> Add-ons -> | extensions |

See also

• Find and install add-ons to add features to Firefox_how-do-i-find-and-install-add-ons

It is possible that there is a problem with the file(s) that store the extensions registry.

Delete the files extensions.* (e.g. extensions.sqlite, extensions.ini, extensions.cache) and compatibility.ini in the Firefox profile folder to reset the extensions registry.

• https://support.mozilla.org/kb/Profiles

New files will be created when required.

See "Corrupt extension files":

• http://kb.mozillazine.org/Unable_to_install_themes_or_extensions
• https://support.mozilla.org/kb/Unable+to+install+add-ons

If you see disabled, not compatible, extensions in "Tools > Add-ons > Extensions" then click the Tools button at the left side of the Search Bar (or click the "Find Updates" button in older Firefox versions) to do a compatibility check or see if there is a compatibility update available.

Thanks everybody for your help,problem solved.