The most reliable way to get an MQ4 file is to contact the original creator and purchase or request the source code.
In early 2014, MetaQuotes updated MT4 to build 600+, changing how files are compiled. Newer versions use binary code instead of byte code, making them virtually impossible to decompile with this legacy tool. Ex4 To Mq4 Decompiler 4.0.432 - Updatedl
Used by traders and developers to modify, debug, or learn from compiled EAs and indicators. The most reliable way to get an MQ4
Specifically aimed at .ex4 files, which are the compiled versions of .mq4 source files. MetaQuotes updated MT4 to build 600+