Here i will show you how install .net framework 3.5 in windows 8 or 8.1.
Step 1 : Insert Windows 8/8.1Usb Bootable / DVD
Step 2 : Run CMD as Administrator (Admin)
Step 3 : Enter the command in Command Prompt
Seep 4 : dism /online /enable-feature /featureName:NetFx3 /all /limitAccess /source:f:\sources\sxs

(Where 'F' is your bootable Pen drive or Windows DVD Drive)
Than ENTER

The .NET Framework is an integral part of many applications running on Windows and provides common functionality for those applications to run. For developers, the .NET Framework provides a consistent programming model for building applications. if you are using the Windows operating system, the .NET Framework may already be installed on your computer. Specifically, the .NET Framework 4.5 is included with Windows 8 and the .NET Framework 4.5.1 is included with Windows 8.1.
but The .NET Framework 3.5, however, is not automatically installed with Windows 8.1 or Windows 10, and must be separately enabled to run applications that depend on it.
now open command prompt As administrator and type command :(Specifies the 'F' is your Bootable with Windows 8.1 File/ Windows 8.1 DVD Drive Location)

свернуть