1. Right click on Taskbar then task manager
2. Click on Process tab and Find any instance of Apache that is running
3. Close this instance and wait a moment, if another instance appears, close that one too.
4. Now in Program Files->Apache Friends->Xampp->Control Panel, click start Apache. It probably will work.
5. If this does not solve the problem, click on the check box next to Apache saying “Svc” (Service) and restart the PC. This usually works.
6. If your windows update had damaged Apache installation to a greater extent, you may need to reinstall the XAMPP altogether.