Hi friends, If u are having problems with installing .net framework 3.5 here s the fix.

Can't install .net framework 3.5 (KB951847) x86

Start Windows Update in safe mode:
1.To start Windows in safe mode, click the Start button, type msconfig in the Search box, and then, in the list of results, click msconfig.exe. If you are prompted for an administrator password or confirmation, type the password or provide confirmation
2.In the System Configuration dialog box, click the Boot tab
3.Click the Safe boot check box, click Network, and then click OK
4.In the System Configuration dialog, click Restart. This will restart your computer in a special way called safe mode with Internet access
5.Click to open Windows Update
6.In the left pane, click Check for updates, and then wait while Windows looks for the latest updates for your computer
7.If any updates are found, click Install updates. If you are prompted for an administrator password or confirmation, type the password or provide confirmation
8.Once updates are installed, restart your computer, click the Start button, type msconfig in the Search box, and then, in the list of results, click msconfig.exe. If you are prompted for an administrator password or confirmation, type the password or provide confirmation
9.In the System Configuration dialog box, click the General tab, click Normal startup, click OK, and then click Restart
10. Start Windows Update with a clean restart of Windows
Click the Start button, type "msconfig" in the Search box, and then click msconfig.exe. If you are prompted for an administrator password or confirmation, type the password or provide confirmation
11.On the General tab, click Selective startup, and then clear the Load startup items check box
12.Click Services, click Hide all Microsoft services, and then click Disable all
13.Click OK, and then click Restart
14.Click to open Windows Update
15.In the left pane, click Check for updates, and then wait while Windows looks for the latest updates for your computer
16.If any updates are found, click Install updates. If you are prompted for an administrator password or confirmation, type the password or provide confirmation
17.Once updates are installed, restart your computer. Click the Start button, type msconfig in the Search box, and then click msconfig.exe. If you are prompted for an administrator password or confirmation, type the password or provide confirmation
18.On the General tab, click Normal startup, click OK, and then click Restart
If the problem persists after you have followed the steps above, go to the Knowledge base article on Windows Update error 80070020 on the Microsoft website for additional steps you can try, or go to the Windows Update Support Center website to request