lost file

Google suggests that your platform SDK may be outdated or your include paths may be such that your #include directive is looking in the wrong place.

how do I update my platform SDK

You might try searching all files and folders to find out where the file is at on your hard-disk then make sure you're #include directive is set to include that folder. (Project->Properties->Configuration Properties->C/C++->General->Additional Include Directories in Visual Studio.)

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how do I update my platform SDK

You can download the latest version from Microsoft's website. You can use Google to search for the exact page.