Problem changing desktop background in Mountain Lion (10.8.1)

I have performed an upgrade to the latest Snow Leopard and now to Mountain Lion (10.8.1). Post upgrade my desktop background isn't no longer changing. The background will not change when I try and select a different background via system preferences. Even if I reset it to the default background the same behavior persists. My system has exhibited this problem for almost 7 months now, I have this ugly plain blue background I cannot look at any more. Can anyone offer a solution that might resolve this?

Solution 1:

Try deleting /Users/username/Library/Preferences/com.apple.desktop.plist

Then, empty your trash and reboot. This file stores the preferences for desktop wallpaper and deleting it will give you a clean slate. Your system should default to the standard Mountain Lion wallpaper.

Solution 2:

Open Terminal (Applications/Utilities/Terminal.app) and paste this command

rm ~/Library/Preferences/com.apple.Desktop.plist

press 'return' on the keyboard.

Log out, log back in again. Change the wallpaper to what you want. Log out, log back in once more to test.

Any improvement?

Solution 3:

My steps (on El Capitan 10.11.2):

• Deleted com.apple.desktop.plist- problem persisted
  
• Replaced /System/Library/CoreServices/DefaultDesktop.jpg (req. disabling System Integrity Protection here) - problem persisted
  
• Repaired permission for /System/Library/CoreServices/DefaultDesktop.jpg as detailed here - problem SOLVED (can choose new desktop image via Sys Pref. as normal)