Toddler won’t sleep!

AZ

My daughter is 21 months old and she is a nightmare to put to sleep at nap time or bedtime. Sometimes she skips nap time during the day all together (after 2 hours of me patting her, singing to her, closing the curtains, etc). Once she’s asleep she is fine but it’s the putting time sleep but which I’m really struggling with. Does anybody have any tips? I’ve come to the point of putting the tv on and letting her fall asleep watching it, this usually takes forever too!!