Hi Suresh,
That's rather a big haystack in which to find the needle!
Why don't you know what changes have been made in the system? And what about the Test system - is the process still working there? - if so, just compare the settings.
Can't you ask whoever set it up originally, to set it up again? Alternatively, follow the steps in the GTS Configuration Guide.
If you have a developer, or you have developer skills yourself, debug in Function Module /SAPSLL/CD_MM0B_R3 to see what's going on there.
Regards,
Dave