Help my 2 year old won’t sleep

My son has always been a great sleeper sleeping from roughly 19.00/20.00-07.00/08.00 plus a 1-2 hour nap. Almost over night he has decided he doesn’t want to go to bed. He stands crying at the bottom of his cot and tries everything (he wants a cuddle, wants a drink of water, wants his nappy changed) and he is taking 1-3 hours to fall asleep at night. He won’t go for naps unless he falls asleep in the car. I still try to get him to nap but he’s still awake an hour later. He’s stared getting up really early and crying and won’t go back sleep. Today he woke at 05.30am and hasn’t had a nap. I put him to bed at 18.30 with the aim of him being asleep for 19.00. It’s now 20.30 and he’s still awake he won’t even lye down in his cot. He’s now been awake for 15 hours without a nap and wont sleep. He has never been awake this long. How can

I get him to sleep. Please tell me this is a phase.