Install .NET frameworks in windows 8 manually.

1. Try to add the feature. Click here to see the tutorial.
2. If it fails to add the feature you have to add the feature manually.
3. First insert the window 8 DVD.
4. Open the command prompt as administrator and type the below command,

Dism.exe /online /enable-feature /featurename:NetFX3 /All /Source:k:\source/sxs/LimitAccess

dism /online /enable-feature /featurename:NetFx3 /all /source:k:\sources\sxs

the Source k: is the DVD drive

6. To check the installation have been done successfully go to control panel Programs and Features, Programs and Features click Turn Windows features on or off and verify the check box is checked for the .net frameworks.