Cannot install .NET Framework 3.5 features on Windows Server 2012

Cannot install .NET Framework 3.5 features on Windows Server 2012

Hi friends recently I am trying to install .Net Framework 3.5 on Windows Server 2012 R2. But I end up with this error:

Installation of one or more roles, role services, or features failed. The source files could not be found. Try installing the roles, role services, or features again in a new Add Roles and Features Wizard session, and on the Confirmation page of the wizard, click “Specify an alternate source path” to specify a valid location of the source files that are required for the installation. The location must be accessible by the computer account of the destination server.

I try again to install a server restart but no luck, at last I mounted DVD and try this:

1. Open Add Roles and Features Wizard

2. Select .NET Framework 3.5 Features and then click next,

3. Select Specify an alternate source path link in the Confirm installation selections screen.

4. Path: D:\Sources\SxS and then click OK.

5. Finally click Install button.