If you have ever downloaded a trading robot only to find it is an .ex4 file (executable) rather than an .mq4 file (source code), you have likely Googled the phrase:
If you are dealing with a very old EX4 file (created before 2014), you might find success using legacy software like "EX4 to MQ4 Decompiler 4.0.432." How To Convert Ex4 To Mq4 Free
If you want, I can: