Are you able to find stdio.h on your computer??
If so, then you may have directory problem.
When you #include <stdio.h>, the angle brackets tell the preprocessor that the file is located on a pre-defined path. These paths are the "standard places" and are part of your build project settings. If the paths are not correct, you will get an "unable to open stdio.h".
When you #include "stdio.h", the double quotes tell the preprocessor that the file is located in the present working directory (PWD). This is usually the directory that contains your project files. If the file is not there, then the search for it proceeds as if you coded #include <stdio.h>.