[Joomla] Joomla 3.x. Troubleshooter. CSS files are missing in template manager

In some cases CSS editor is missing in Joomla 3.x. admin panel. You can see the list of files, but they can not be edited.

You can go to Extensions -> Templates Manager -> Templates, choose the default theme – ThemeXXXX to check:

We should follow these steps for troubleshooting the issue:

• First of all, we need to check database and prefix table for the website. From Joomla Admin Panel, go to System -> Global Configuration ->Server tab to check the database name and table prefix:
  
  

   

• Go to phpMyAdmin -> Select the right database name for this Joomla website from the left side:
  
  

   

• We should make a backup for this database just in case. Click Export tab -> then click Go button -> Click OK button and save .sql file.
  
  

   

• Open SQL tab:
  
  

   

• Add the code below to the content box:

  ?

  1 2	UPDATE `jos_extensions` SET `params` = '{"template_positions_display":"0","upload_limit":"2","image_formats":"gif,bmp,jpg,jpeg,png","source_formats":"txt,less,ini,xml,js,php,css","font_formats":"woff,ttf,otf","compressed_formats":"zip"}' WHERE `jos_extensions`.`extension_id` =20;

  
  

   

• Make sure you replace all ‘jos_‘ with your prefix table that you have checked from step 1. Press ‘Go‘ button:
  
  

   

• Log into Joomla admin panel. Go to Extensions -> Template Manager‘ -> Templates -> ThemeXXXX. Refresh the page to see that now we have access to the template css files:
  

Source: http://www.templatemonster.com/help/joomla-3-x-troubleshooter-css-files-are-missing-in-template-manager.html