how can one convert .ex4 file into .mq4 file ?
Decompiled code is stolen code. Either you are a thief, a fence, or the receiver of stolen (intellectual) property. Either way we will not be an accomplice after the fact to theft. See also https://forum.mql4.com/41864#490649
Don't tell us you found it on the 'net: if someone stole your bank details and uploaded them on to the internet, is it OK for everyone to use them because "someone uploaded it, I don't know why I can't use that"?
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