Apache won't start in wamp

If you have an issue in the httpd.conf or any files included by it there are a couple of ways to find out what the problem is

First look at your Windows Event Viewer. Click on the Windows link in the menu on the left, and then submenu Applications. Look for messages from Apache with the red error icon.

Secondly, open a command window, then CD into \wamp\bin\apache\apache2.x.y\bin, replace x,y with your actual version. Now you can run this command to get Apache(httpd) to vaidate the httpd.conf file.

httpd.exe -t

This should give errors with line numbers related to the http.conf file. It stops on the first error, so you will have to keep running it and fixing the error and then run it again until it gives the all OK message.

That is what I did and it helped me to find out what my Apache-PHP needed:

C:\Users\Admin>cd C:\wamp\bin\apache\apache2.4.9\bin

C:\wamp\bin\apache\apache2.4.9\bin>httpd -t
Syntax OK

C:\wamp\bin\apache\apache2.4.9\bin>httpd -k start
[Thu Apr 23 14:14:52.150189 2015] [mpm_winnt:error] [pid 3184:tid 112] 
(OS 2)The system cannot find the file specified.  : AH00436: 
No installed service named "Apache2.4".

C:\wamp\bin\apache\apache2.4.9\bin>

The most simple solution:

Uninstall and reinstall WAMP (do not even try to set it up on top of existing installation - it would not help)

P.S.

If you wonder how did I get to this situation, here is the answer: I was trying to install WAMP and it throws me an error in the middle of installation saying:

httpd.exe - System Error

The program can't start because MSVCR110.dll is missing from your computer. 
Try reinstalling the program to fix this problem.

OK

I got and installed Microsoft Visual C++ 2012 Redistributable from here http://www.microsoft.com/en-us/download/details.aspx?id=30679#

And it gave me the "dll" and the MYSQL started working, but not Apache. To make Apache to work I uninstalled and reinstalled WAMP.

Use apaches startup debug tool from command:

httpd.exe -e warn

1. press Win+R
2. type cmd and press enter
3. goto directory which contains your apache httpd.exe file. for example if your wamp is installed in e:\wamp type cd /d e:\wamp\bin\apache\ApacheX.X.X\bin in cmd and press enter.
4. type httpd.exe -e warn (or httpd.exe -e debug for more details) to see error message about problem which is prohibiting apache to start.