1. OFFLINE METHOD.

1. Insert the Windows installation media.
2. Open Command prompt with Administrative privilege.
3. Copy paste this command to your command prompt and click enter.

Dism /online /enable-feature /featurename:NetFx3 /All /Source:E:\sources\sxs /LimitAccess

NOTE: The E: in the command denote your DVD drive check to see if yours is E: if not make the necessary change. To Check click on the folder icon on your task-bar.

2. WINDOWS UPDATE METHOD

This behavior can be caused by network, proxy, or firewall configurations or by network, proxy, or firewall failures. To

resolve this problem, try to connect to the Microsoft Update website.

1. Swipe in from the right edge of the screen, then tap Search. If you're using a mouse, point to the lower-right corner

of the screen, then click Search.
2. Enter Windows Update in the search box, tap or click Settings, and then tap or click Install optional updates.

3. CONFIGURE GROUP EDIT POLICY METHOD

1. Click the Windows button type Run in the search bar. Paste this command gpedit.msc
or After clicking the windows button Type group policy in the search bar and click on Edit group policy.

2. Click Administrative Template.
3. Click on System.
4. Double Click on Specify settings for optional component installation and component repair Group Policy setting
5. Select Enabled
6. Select the Contact Windows Update directly to download repair content instead of Windows Server Update Services (WSUS) check box.
7. Click Apply and then ok.

4. TURN WINDOWS FEATURES ON/OFF

1. Click Windows button. From the Search bar Type Programs and Features
2. Click Turn Windows features on or off
3. Select .Net Framework 3.5(includes .Net 2.0 and 3.0) from the check box and click ok.
4. Open Command prompt with Administrative privilege and paste this command gpupdate /force

5. IF NON OF THE ABOVE WORKS, TRY COMBINATION OF THE 4 .