Can anyone provide header file of WConstants which was used in earlier versions of arduino before 1.0 like 0023 etc
Pick the version you need from here, download it and extract the WConstants.h file.
You shouldn't need it.
All the constants are in Arduino.h which is normally already included or it can be manually included.
WConstants.h was a simple wrapper that included wiring.h
All that has been moved into Arduino.h as of IDE 1.0
Even if you were to get those files, it would likely not work as it will probably result in duplicate defines since they will collide with the defines in Arduino.h
Best thing is to fix the code to not need WConstants.h as it is no longer used/needed in the 1.x IDEs.
--- bill