Startup Sound Midi: Windows 95
If you want an actual .mid file that plays this on any GM synthesizer, you can create it in a DAW like Reaper or MuseScore. Search for "Windows 95 startup sound MIDI remake" — many fan-made versions exist, but they will sound different depending on your sound card's MIDI patches (e.g., Microsoft GS Wavetable Synth vs. a Roland Sound Canvas).
However, if you need a that sounds like the Windows 95 startup sound, you must understand: you cannot convert the original WAV to MIDI and get the exact same audio. MIDI has no built-in instrument samples—it depends on your sound card's wave table or FM synthesis.
The Windows 95 startup sound was not a MIDI file; it was a composed by Brian Eno . It is a few seconds of synthesized, ambient piano-like chords.