'Play' button & 'Enable MIDI Input' buttons do not work

Everything worked well until I tried to hook up my keyboard via MIDI to my computer. The computer did not register the cable, and I checked Edit>Preferences>I/O, and the keyboard was checked in the PortAudio section. It still would not work, and when I went back to MuseScore after a break, the PortAudio section had no device that could be checked and neither the 'Play' button nor the 'Enable MIDI Input' button would work and look like the Note Input buttons during a playback. Can anyone show me how to fix this and get the MIDI input working? Thanks