Playing the audio of my score

My score does not allow me to listen to the audio. I was able to play it just over a month ago and now that I am trying to edit it and listen to what it sounds like, the score's 'play' button for the audio is grey and unresponsive. Even when I add or change notes, they do not make a sound like they did previously. This is not an issue with my device, as its sound works with everything else. What can I do to fix the problem?