If the Microsoft .NET Framework 3.5 component is not installed on your computer or if it is damaged, the component must be installed or repaired.
To install or repair Microsoft .NET Framework 3.5:
Close all open applications.
Click the Windows Start button and choose Run.
Enter control in the Open field and click OK. The Control Panel window opens.
Double-click Add or Remove Programs.
Search the list of currently installed programs for Microsoft .NET Framework 3.5:
If the program isn't listed, install it:
Click here to download it from the Download .NET Framework 3.5 Service pack 1 from Official Microsoft Download Center
If the program appears in the list, repair it:
Select Microsoft .NET Framework 3.5, and then click Change/Remove.
Select Repair, and then click Next.
When prompted, restart your computer.