I have windows 10 now and I can't find the log file!!!
Type '%temp% in Windows 10 file Explorer.
if you mean the IMatch log file, you can open it via Help menu > Support > View Application Logfile.
To find the folder holding the IMatch log file, do as jch2103 wrote above. Search for log file in the IMatch help index to find the corresponding help topic, which explains all that.
Thanks!