Section A- If you already installed XAMPP,try this first before anything else:
1: Close XAMPP Control Panel v3.1.0.3.1.0
2: Go to "C:\xampp\apache\bin" (C:\xampp\is the default installation directory).
3: Start Apache directly without the control panel by clicking on the httpd.exe file.
4: Now to test if its working, go to your internet browser and open the url "http://localhost/". If its working, you should see the XAMPP Welcome page. If its not working, then uninstall completely XAMPP and go to Section B.
Section B- XAMPP is not installed yet or is uninstalled.
First thing to do is to shutdown Microsoft - ISS services.
1: Open Control Panel by clicking the Start button, then clicking Control Panel.
2: Select control panel view classic.
3: Click on Programs and Features;
4: Select Turn Windows features on or off
5: Uncheck the Internet Information Services box then press OK (on the picture it is checked). Dont worry, you could re activate it later if you got any problems.
6: Install XAMPP. Again, Apache will not work if you try to start it with the XAMPP Control Panel v3.1.0.3.1.0 software. Because has i said, theXAMPP Control Panel is also part of the problem. But now, you should be able to start Apache directly.
7: Go to "C:\xampp\apache\bin" (C:\xampp\is the default installation directory).
8: Start Apache directly without the control panel by clicking on the httpd.exe file.
9: Now go to your internet browser and open the the url "http://localhost/". You hould see the Welcome XAMPP page.