I was doing some work on the servers tonight, and as part of that installed the latest batch of Windows updates. Restarted the servers, and continued working on something else. A little while later my Dad texted me, and said the blogs were down. That’s strange I thought, everything looked like it was running fine. So I got on a test connection and loaded up my blog, only to find this message:
Your PHP installation appears to be missing the MySQL which is required for WordPress.
Bizarre! I hadn’t changed anything with WordPress, PHP, or MySQL. So I entered the message in Google and started going through results. (As an aside, is it just me or is the sentence grammatically incorrect? Specifically the part that says “the MySQL”…)
Lots of people have had this problem, apparently, and I went through dozens of search results until I found this one. His first five steps are the same as many other solutions, but his sixth step was new, and it actually worked for me:
add an environment variable “PHPRC” with the value of your php directory, this is key
That was key indeed. I have no idea why I didn’t need that before, and I have no idea why it makes things work now, but I’m glad it does. If you are unsure of how to add an environment variable, see this Microsoft support page (the steps are the same in both XP and Server 2003).
I suspect the solution to this problem is slightly different for everyone, but hopefully if you stumble across this post the PHPRC suggestion will help.
Read: Fighting Monsters
MasterMaq's Blog 
Glad to see someone helped by that! It’s by far the most popular article i’ve done.
Keep on keepin on!
Well I’m glad you posted it, it definitely helped me…thanks!