1. Double check to make sure that access to PC settings has not been disabled.
2. Press the Windows + R keys to open the Run dialog, copy and paste the path below into Run, and click/tap on OK.
3. Check to see if you have the PC settings (aka: Immersive Control Panel) shortcut. (see screenshot below)
4. Do step 5 or 6 below depending on if you already have the PC settings shortcut.
5. If you do have the PC settings shortcut, then go to step 7 below.
6. If you do not have the PC settings shortcut, then click/tap on the download button below to download thePC_settings.zip file below for a clean copy.
A) Save the .zip file to your desktop.
B) Open the .zip file, extract (drag and drop) the Immersive Control Panel (aka: PC settings) shortcut to your desktop.
C) Move the Immersive Control Panel (aka: PC settings) shortcut into the Programs folder in step 2. (see screenshot below step 3)
D) If prompted, click/tap on Yes, Yes, Continue (UAC), Yes, and Yes to approve. (see screenshots below)
F) If you are still not able to open PC settings, then go to step 7 below.
G) If you are able to open PC settings now, then you’re finished and can stop.
7. Open an elevated command prompt.
powershell -ExecutionPolicy Unrestricted Add-AppxPackage -DisableDevelopmentMode -Register $Env:SystemRoot\ImmersiveControlPanel\AppxManifest.xml
NoteHKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\CurrentVersion\AppModel\Repository\Packages
error 0x8007064A: Cannot register the request because the following error wasencountered while initializing the windows.repositoryExtension extension: The
configuration data for this product is corrupt. Contact your support personnel.
8. Test to see if you are able to open PC settings now.
9. If you are still not able to open PC settings, then see: Fix Store Apps and Tiles that are Not Working or Responding in Windows 8 and 8.
Source : http://www.eightforums.com/tutorials/42001-pc-settings-fix-restore-windows-8-1-a.html