why when i install iTunes on my computer it says that there is an error applying transforms?

Hello Nour_Helaly60,
Sorry to hear that you are experiencing issues with installing iTunes. That is something that can be fixed with a little troubleshooting.
Let's start with the article below. It will walk you through ensuring that Windows is up to date as well as running the installer as an administrator. Let me know if this helps or if you need further assistance.

If you can't install or update iTunes for Windows
https://support.apple.com/en-us/HT201668
Take care

At a guess your Windows system language is set to Arabic. There appears to be an issue installing the current build of iTunes in these circumstances. Temporarily change to the language to English or another supported language, install iTunes, and then restore your language preferences.

See http://windows.microsoft.com/ar-sa/windows-vista/change-the-display-language for advice on changing the language.

See Error applying transforms. Verify that the specified transform paths are valid. for more on this error.

tt2