Hi Arun,
Could you check "Start Options" of your process?
Is it "Auto-start"?
If so,
what is "Start Event"? --- "Create" or "Update" or "Create and Update"?
"Do not start a new process if one is already running" is checked?
Is there any condition defined in "Start Conditions"?
For example,
if your process uses "Do not start a new process if one is already running" option and prior process is stuck, the new process will not be invoked.
Regards,
Shoichi