In Windows 8 or Windows Server 2012, open a Command Prompt window with administrative credentials (that is, choose Run as administrator).
To install the .NET Framework 3.5 from installation media located in the D:\sources\sxs directory, use the following command:
DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:d:\sources\sxs
Use /All to enable all parent features of the .NET Framework 3.5.
Use /LimitAccess to prevent DISM from contacting Windows Update.
Use /Source to specify the location of the files needed to restore the feature.