I can't play any notes that require me to use my right hand when playing. My next lesson is Thursday when I can ask my teacher but I would like to practice before then, if possible. There doesn't seem to be anything wrong visually (dents, tears in the pads etc). Does anyone have any idea what could be wrong? It was perfectly the last time I played and now this time it's just not working. What is wrong and how can I fix it?