Need Advice on Putting 21 Month Old down for His Naps. Will Not Sleep in Crib

It takes time... i did it with my son at 9 months old.. he would cry and cry.... the first time was 45 mins.. it was hard.. it was not screamng the whole time because he would stop and play and whine and lay down and yada yada yada the next day it was 30 then 30 then 20 then 15 then I GAVE IN and back up to 30 then the next day i laid him down and that was it.....

everytime at the same time, everytime same routine..

I would say ok,lets sing songs/read a book and go night night ok.
I would sing a song to him, hug him real tight tell him I love him, pat his back a little and say ok, its night night time....
he would get relaxed and lay down...

eventually he would tell me it was time and would walk into the room and climb in his crib.. maybe let him to do that.. but dont give in.. just find a comfortable spot.. maybe give him a toy etc.

First off, I firmly believe that going without a nap shouldn't even be an option with a kid under 3 (and most need it til age 4). Their brains and bodies physically need the rest.
As long as he isn't climbing out of the crib, you should put him in there at roughly the same time each day. You might want to try to be consistent with this for a week or two to get him in the habit of sleeping. You'll probably have to let him cry, however "crying it out" doesn't mean that you let him cry for an hour while you go about your business in another part of the house. You'll probably have to peel him off of you and walk away to him screaming, which is hard. You just have to remind yourself that a week of difficulty will pay of big rewards -- short term pain for long term gain. After that, you could check on him periodically -- first in 5 minutes, then 10, then 15 etc. You can pat him, talk to him, try to do what you can to soothe him without picking him up. Now, with my first child, picking her up for a quick hug was all she needed when we went back in and she'd go right to sleep. With my second, we couldn't pick him up because it would basically re-set the clock after we'd been at it for half an hour. We learned that we couldn't even take a peek in there before the first 20 minutes passed because it only extended the crying.

Another method is in a book by Kim West called "Good Night, Sleep Tight" and she recommends sitting in a chair by the crib while the baby/child cries. From there you soothe, talk, etc. (but still don't pick them up). Gradually, over a period of about 2 weeks, you move your chair closer and closer to the door, then out into the hall, etc.

I don't agree with the crying out thing but that's just me. I went through this for a little while with mine. I just made sure and put her down around the same time twice a day in her crib. WHen she would cry and sit up I would immediatly lay her back down and tell her it was nap time. This happen over and over and over. I never picked her up. One day this went on for a solid hour. At that point, nap time was over and I got her up and deatl with the fussiness until bed time. The next day went way better and naps are a breeze now. The main thing is to not pick them up until nap time is over I think.

I read something somewhere (can't remember where) that really has helped my kids with there naps. It said after a certain age, if your baby/toddler wakes up from nap crying, she is still tired. Let her fuss a bit and she will go back to sleep. A well rested baby wakes up from nap like she does in the morning-happy and babbling. It has certainly worked for me. When my 20 month old wakes up crying and I go get her, she is tired and grumpy the rest of the day. If I let her fall abck asleep, she wakes up much happier. Of ourse a regular and consistent nap schedule will really help too. Good luck!