Apache doesn't start on Windows XP Professional SP3

I have XAMPP installed on my PC, and it works fine. Every service starts fine except Apache. I went to Services in Administrative Tools, and tried to start it from there, without success. I tried XAMPP Shell to run Apache by typing: xampp_cli start apache. That didn't work, either.

I also tried reinstallling XAMPP, turning my computer off/on, restoring the registry from when I first installed XAMPP when Apache worked but still, nothing changed.

Any ideas as to what could be causing this problem?

Look in the Apache logs\error_log to see what the problem might be.

The most likely cause is that something else is already listening on port 80.
The error_log should give you a clue, but you can run

netstat -na -p tcp

To see is anything else is using port 80

I had the same problem and solved it by uninstalling other programs like VPNs that I created – TeamViewer etc.

Reason for this problem is a conflict between ports that are specified for programs.