If ports 80 and 443 were busy when XAMPP started, ports 8080 and 4433 may have been automatically assigned instead. This can cause issues in WordPress, so you want ports 80 and 443 available for XAMPP whenever you're working on your local site.
The problem is almost always caused by a conflicting program (usually Skype!) and it is easy to fix.
If that didn't fix the issue, go directly to the Apache Friends community and ask for help. An experienced user should be able to help you resolve the conflict.