“Unable to open include file” while compiling…

Hello,
I have been frequently facing the following problem while programming in "C": the error message "Unable to open include file." was entered at the time of compiling the program.
I checked the library of files, they are stored in my include folder yet the error message has entered while compiling; why? I would be grateful if anybody solves this.

Message
Compiling D:MYDUMP~1TCMYPROGRA.C:
Error D:MYDUMP~1TCMYPROGRA.C 2: Unable to open include file 'STDIO.H'
Error D:MYDUMP~1TCMYPROGRA.C 3: Unable to open include file 'CONIO.H'
Error D:MYDUMP~1TCMYPROGRA.C 4: Unable to open include file 'STRING.H'
Error D:MYDUMP~1TCMYPROGRA.C 5: Unable to open include file 'STDLIB.H'
Bye
