My DD has just turned 20months and it's almost impossible to get down for a nap during the day!
She's never been a great sleeper anyway from birth but it seems like the older she's getting the more stubborn she is to stay awake all day.
I've tried so many different techniques and purchased a sleep training book a while ago, she can settle herself so I don't think that's the problem.
The only way to get her down for a sleep during the day is to walk her in her buggy until she drops off but that can take upto an hour or longer and then she will sleep for a few hours in her buggy.
Her current pattern is waking at 6 and then being awake until 5 but even then she's not sleeping through. My worry is that it's affecting her as in her behaviour/appetite etc..
I've read that it's important for naps to still be in place at this age to avoid getting overtired.