[fysiks]

This is called de-compiling a plugin. It cannot give you the exact code that was used to generate it, if it's possible at all. With AMX Mod X plugins (since you posted in the AMX Mod X section), there are tools to de-compile a plugin but you have to know scripting very well and how assembly works. Essentially, you have to rewrite the plugin anyways and the de-compiled code can simply give you clues on how things are done.

I'm not sure if there is an equivalent for SourceMod but generally (99+% of the time) it is much easier to re-write the plugin from scratch.