Unable to preview the project even after publishing in Captivate 12.5

Hi, I need urgent help. My project all of a sudden has stopped showing a preview every time I preview link opens but gives a blank screen same happening after publishing. Before the file was perfect the only thing I did was edit the theme. Please help me as I cannot create a new project at the moment as this project was already in review by my client and now this issue is occurring. Can the project be recovered? Thanks