First off, this is not related to Apache not running normally, it works perfectly under normal circumstances. However, I decided today to edit the file that I believe to contain the HTML for phpinfo() (xampp\php\php5ts.dll), no specific reason, I thought it'd be fun to change the PHP logo to some random image. I made a backup, and tried editing. I stopped Apache on XAMPP control panel, restarted for good measure, and it wouldn't start, I made sure that my edits didn't accidentally escape (or un-escape) any characters, so it's valid HTML.
I edited line 29,021 of php5ts.dll, and only changed the src="..." attribute. The original line can be found here. Please note however: the code goes something like <a><img src="base64 for one image" /></a>data:image/png;base64,..., with the second (and the one that displays) image not being in an <img> tag, weird!
Anyways, after editing this line, Apache did not start anymore, did not show any errors in the control panel or in xampp\apache\logs. I did however find a few errors in the Application section of Event Viewer. My error is:
httpd.exe: Syntax error on line 521 of C:/xampp/apache/conf/httpd.conf: Syntax error on line 17 of C:/xampp/apache/conf/extra/httpd-xampp.conf: Cannot load C:/xampp/php/php5ts.dll into server: The Apache service named is not a valid Win32 application.
Line 521 of xampp\apache\conf\httpd.conf is Include "conf/extra/httpd-xampp.conf".
My guess is that the culprit is on lines 17-19 of httpd-xampp.conf:
LoadFile "C:/xampp/php/php5ts.dll" LoadFile "C:/xampp/php/libpq.dll" LoadModule php5_module "C:/xampp/php/php5apache2_4.dll"
Nothing turned up for this error on Google, anyone have any ideas?
Version info for anyone interested: XAMPP Control Panel v3.2.2 [ Compiled: Nov 12th 2015 ]
Try to download PHP 5 for win32.