Keyboard not working

So I opened up MuseScore and tried to write. I typed A on the Clarinet Line to get the instrument to play an A, but the letter didn't work. I typed it over and over, I tried other notes, BCDEF, not one worked, I tried different instruments, didn't work, I tried a new score, didn't work, I restarted the program, didn't work, I re-downloaded the program, didn't change a thing. I have to manually go in and click input note and click the note, and if I type a wrong note I have to stop Note input manually (the N key won't work either) and select the note, and delete it (guess what, my Delete button won't work either.) Making writing scores go from an hour or two to about 5 to 6 hours per section of one song. This is happening only in musescore, as the keyboard works perfectly fine in all other applications.