If you have installed Microsoft Silverlight SDK v4.0, but your Visual Studio displays the message “Could not find Microsoft Silverlight SDK v4.0. Please make sure that the correct version of the Microsoft Silverlight SDK has been installed.” and you cannot edit XAML in designer, so you have the same problem that I encountered yesterday 🙁
But that’s okay, today I will tell you how I managed to restore Silverlight:
1. You can download the following tool from Microsoft to open an instance of regedit as system: http://technet.microsoft.com/en-us/sysinternals/bb897553
2. The following command line will open a “system” regedit:
psexec -s -i regedit
(Note: You have to execute this command line from an “administrator” command prompt [right-click command prompt and click run as administrator])
2. Navigate to HKEY_CLASSES_ROOT\AgControl.AgControl (if you get a message that says “AgControl.AgControl cannot be opened. An error is preventing this key from being opened. Details: Access is denied.” proceed to the “Taking ownership of the key” section)
3. Right click and choose “Permissions”
4. Click “Add”
5. Either add your windows username or your network username in the “Enter the object names to select” and click “Check Names”. Your name should take the proper format. If it does not try clicking “Advanced” and searching for your username. My windows username was the one I used.
6. Click OK
7. Select your new username in the top pane and in the lower pane (Permissions for) check the Allow box next to Read.
8. Click OK
When done, you registry entries should look somewhat like the following along with your user id having full permissions to these registry entries: