The "decompiler50 1 exe new" tool is a decompiler specifically designed to convert EX4 files back into MQ4 format. This tool claims to be able to decompile EX4 files created by the MetaTrader 4 platform, extracting the original source code, including variable names, function names, and even comments.
Ask the original creator for the .mq4 file or hire them for modifications. ex4 to mq4 decompiler50 1 exe new