ALR MIDIEditor 40678
From CockosWiki
Reset all MIDI devices (Cmd ID 40678)
Sections: MIDI Editor, MIDI Event List
Does the same as hitting "Reset all MIDI devices" in REAPER Preferences -> Audio -> MIDI Devices. If a MIDI device happens to hang for whatever reason, you can try to cure it this way without restarting REAPER or the whole system.