What stage are you at? Are you still researching, or have you started writing things? In either case I'd recommend drawing up a list of what you should be getting on with, then breaking it down into smaller parts. Pick the most appealing item on the list to start with (alternatively read that as the least unappealing!), and tackle that. Then once you've done that move on to the next item and so on. I also find that brainstorming in general helps, to make track of where I am now, and where I might go next. Have you agreed deadlines/targets with your supervisors? Did your supervisor give any advice on how to overcome your worry? They're there to guide you through this process, so make sure they help. But it's definitely not too late. I've had much longer periods of down-time (admittedly I'm part-time so schedules are more fluid) and have managed to pick myself up again. Just in the process of doing it now actually, though a looming deadline helps. Good luck!