I agree with Naomi, I think this is overtiredness. He is extremely young not to nap (how many days is he at nursery and how long does he nap for there?) and so if you can't get a nap (are you trying at all now? Car? Stroller?) bedtime needs to come much, much earlier. My LO who is a year and a half older goes to bed at 6.30pm with no nap, and gets up around 6.30 most days. If his body clock is set to sleep at 9pm right now though I suspect you will likely have to do this in stages. I might even suggest implementing a calm wind down routine aiming to have him in bed around 8.45pm for now, to be asleep for 9pm. Then gradually moving this earlier by 15 mins every 3 days.
If he normally naps at nursery at 1pm or so have you considered putting in his bed at home at that time, and then using WIWO/silent return, keeping him in his room/bed for at least 45 mins? I wonder if you did this every day whether he may in fact start napping for you again, and that would have the advantage of a consistent routine. What do you think?