No Instruments and No Sound

Whenever I open up Musescore 2.0 the first thing that it says is that [Cannot Read File :/My_First_Score.mscx: Unknown Error] But then when i try to create a new score i am not able to make a template from scratch When I get to the instruments nothing shows up so there are no instruments to pick from. I can upload some scores I have from an old song and have them play and edit them and everything but besides that I can not make anything new. Is there a reason that the instruments don't show up or what should I do?