Any file to store the whole process in ERPNext, Any log file or something
Ummm… exactly what “whole process” are you trying to store?
There are thousands of processes in ERPNext so you need to be much more specific.
if any .log file ?
There are many different .log files supporting many different functions of the ERPNext servers.
If you are asking about some all inclusive forensic recording of every stock movement, ledger change, price change, etc, then the answer is NO.
Remember, this is an open source project. The thing you are looking for barely exists on top $$ paid licensed systems.