Even there is many better 3rd party Joomla! SEF plugin in, Joomla!'s default SEF plugin do a good role in making Joomla! a better CMS. In my journey in developing my first Joomla! made website. I accidentally uninstalled its default SEF plugin. This incidence doesn't alarm me since I will replaced it with a better 3rd party SEF plugin. After I finished installing my new SEF plugin, I checked the website and a cold sweat slowly flow all over my face. All of the website images are suddenly not appearing.
As I tirelessly working for a solution, I found out that this scenario can happen when you uninstalled the Joomla! default SEF plugin. I bet you read this post because you also accidentally uninstalled this precious plugins. Don't worry, you're in the right track right track of restoring your Joomla!'s default SEF plugin. You'll just need to follow the post below.
PROBLEM
Accidentally uninstalled or delete Joomla!'s Default System Plugin.
SOLUTION
First and foremost, I'll assume that you know how to navigate to Joomla! without any graphical instructions.
STEP 1
Download Joomla! installer here. Make sure the version you've dowload is matched on your current Joomla! version.
STEP 2
Extract your Joomla! installer.
STEP 3
Go to [joomla!_path]/plugins/system/.
STEP 4
Find a folder with a name of sef and compress it as zip format.
STEP 5
Navigate to your Joomla! plugin installation wizard and installed the compressed zip files (sef.zip).
Now, reload the page and see if all the mess on your websites is fixed. Don't hesitate to trigger the comment button if you have any question. Cheers!