Midi LPK25

Last time( first time) I plugged in the above keyboard & selected midi input, all i needed to do was turn up the volume for my keyboard/computer/musescore setup to work.
This time I get no sound and no clues about where to look to resolve any issues.
So I know it has worked but can't get it going now.
Any kind person able to point the way ?

Between attempts I did try to upgrade from Musescore 2 to 3 but got an installation package incompatibility message - I don't think that should have any impact on my situation.