If you are using XAMPP to run a local web server and it so happen that you can not start the Apache Web Server this its quite frustrating right? If you run Apache it will start then immediately will stop?
The culprit is Skype! Skype by default uses port 80 and 443 for its incoming connection thus conflicting Apache default port 80.
The solution for this is to change the default port of Skype.
Go to Skype > Options > Advanced Settings > Connections > Uncheck (Use port 80 and 443 as alternatives for incoming connections). After doing this you can now run Apache with no problem.