This sometimes can be a problem if WSUS/GPO is not set up properly to allow install missing packages and windows update is configured to use WSUS.
Insert your windows installation disk. Make a note of partition number you are using for it eg: D/E
Go to Start -> Open up command line by typing cmd -> Right Click Run as Administator
then type the following
C:\Windows\system32>dism /online /enable-feature:NetFx3 /All /Source:e:\sources\
This will allow you install missing package.