I have been having the exact same problem as you. And I (literally) solved it 2 minutes ago.
I am running Apache 2.4 64 bit on Win 7.
The version of php I downloaded gave me two php.ini files:
1)php.ini-production and
2)php.ini-development
I thought that was all gravy and every time I made a change to one, I did the exact same thing to the other.
When I first encountered the problem I loaded index.php (on my local server) and looked at the sixth box from the top called "Loaded configuration file". It simple said "nothing."
I then referenced this page and found how PHP (once started) goes about looking for the php.ini file. I tried putting both the development and production (referenced above) files in all the directories that the above link specified. Nothing.
Then I thought, what the hell it's worth a shot, and changed the php.ini-production to just "php.ini".
Bam. It started working. Such a simplistic fix but I suppose it makes sense as to why Apache wasn't able to find "php.ini." The file didn't exist verbatim.
I really hope this helps, running into this problem sure sucked.
And I'm sorry if any of this seems patronizing because it is so simple. I always troubleshoot from this site and so many of the answers require more than a fundamental understanding of a subject, and since this seems like a problem(and a solution) that beginners will struggle with, I thought I would spell it out in a way that I would have appreciated 6 months ago.