Install .NET Framework Offline on Windows 8

Windows 8 comes with the net 3.5, you need turn it on. Go to control panel>programs and features>turn windows features on or off>click the net3.5, then OK)

By clicking the windows feature for dot net 3.5, it will give you a window to install the feature by downloading from Microsoft. But dot net 3.5 is already included in the installation media of Windows 8.

Run Command Prompt "cmd.exe" with Administrator Account

then paste this command without quotes

"dism.exe /online /enable-feature /featurename:NetFX3 /Source:X:\sources\sxs /LimitAccess"

where X is the location of the installation media.

This command is only for x86 version of Windows 8.