2 year old sleep regression

As

My son turns 2 next month and we are hard core nap fighting. The last couple weeks have been a pain to get him to try to sleep. I work from home so I try my best to do a prenap routine or calm down time, we go to the park everyday before I work to burn energy as well. He used to go down between 11 and noon and sleep 2-3 hours and he fell asleep within 10 minutes of going in his room. Now he either won't nap at all, won't go down until 2-3 or falls asleep in random places and will not stay in bed to fall asleep. I don't know what to do anymore, he's tired but refuses to sleep for naps, I also don't know how long I should go before giving up each day.