Cannot start Apache server from XAMPP Control Panel.
First source of the problem is usually that the port 80 is in use by other applications. We can run “netstat” on command prompt line, to view which applications use different network ports. One of the applications that use port 80 constantly is Skype. This can be disabled from:
Tools > Options > Advanced > Connection > Un-tick “Use port 80 and 442 as alternatives for incoming connections”
The second most often problem source can me an error in the virtual hosts configuration:
check the httpd-vhosts.conf file,
the configuration doesn’t support spaces between the rights for the directory, and make sure all tags are closed, according to the XML convention.