iTunes not able to install on my windows 8

First, are you installing the correct iTunes version for your Windows OS? See turingtest2's excellent iTunes for Windows Troubleshooting page at:

Troubleshooting issues with iTunes for Windows updates

From that page you can download just about any version of iTunes appropriate for your OS. It also gives procedures to fix common iTunes installation problems, most of which are:

The general troubleshooting advice when iTunes fails to install properly (and reinstalling or repairing it does not work) is to remove not only iTunes but all related components, reboot, remove the target installation folders and reinstall.

With that particular error try repairing Apple Software Update from the programs and features control panel, then remove it and see if iTunes will install normally. See the user tip for further advice if required.

tt2