How to Replace Misplaced OS Files My Mom accidentally moved some system files on her Macbook Pro and did something so they can't be restored back to where they were and now some apps aren't working anymore. Is there a way to repair the installation of Mac OS or a way to figure out where these files should go? She doesn't have Time Machine set up by the way so that isn't an option.

Here is the list of files that she moved:

ATASMARTLib.h
Conversion.h
glut.h
IOAccelSurfaceConnect.h
IOCDTypes.h
IOFDiskPartitionScheme.h
IOFireWireLib.h
IOGraphicsInterface.h
IOGraphicsInterfaceTypes.h
IOGraphicsTypes.h
IOMacOSVideo.h
LogicAUProperties.h
USB 14-18-03 2.h
USB 14-18-03 3.h
USB 14-18-03 4.h
USB 14-18-03.h
USB.h
vDSP 14-17-08 2.h
vDSP 14-17-08.h
vDSP.h
Yes

Simply take the original installation disc that came with the Mac and re-install OSX, afterwards just do a system update to bring it up to the latest version.

When OSX is installed over an existing installation, all settings and applications are preserved, and this should resolve all issue with the OS.

However, as @Kyle pointed out in the comments, the files moved are only header files used for compiling, and should not be affecting the working OS, and since the actual OS files are not available via the Finder, highly unlikely that she copied actual system files, unless she used Terminal.

If the applications still don't work after doing this, then those specific applications needs to be re-installed individually. The above procedure will work for all applications supplied by Apple as part of the OS.