I had the same trouble. You first need to uninstall .NET 4, then install .NET 4 "Full" from here: http://www.microsoft.com/en-us/download/details.as
Then install the patch KB2468871 from here: http://www.microsoft.com/en-us/download/details.as
After installation, you will see both .NET 4 Framework Client Profile and .NET 4 Framework Extended listed in the Programs and Features screen, and updates for both listed in Installed Updates.
Log into access your profile, ask and answer questions, share ideas and more. Haven't signed up yet? Register