A somewhat unusual music request...(need a modified digital rendition of a MIDI)

[Akril15]

I have a single music piece that needs to be slightly altered. However, I don't have the original project files (just an .ogg of the finished product, as well as a few related files), so I hope it can be easily recreated along with the changes I need. Please PM me if you're available.

EDIT: I had another look at my files, and it turns out that I have a MIDI of the instrumental, however it seems to be missing some parts from the digital version. This means that it would be less of a matter of reproducing the song from scratch, and more of a matter of creating a digital version of this MIDI with some minor modifications.

EDIT 2: Help found!