Instrument only shows one note

Hi, I just downloaded musescore 4.4 and when I opened it the violoncellos was only written with a's in a percussion clef. I tried to open a back up file but musescore couldn't open it. I tried changing the clef back to a bass clef but that also didnt work. I do not think I changed the clef to a percussion clef because when I tried to change the clef back to percussion it just did not do that. When I select a note it could not recongnize it's pitch. Surprisingly the playback still played the right notes. I use windows.