i'm trying to fing where to contact about staying in a yurt in inner mongolia for 4 days

Well, to be honest, few yurt owners operate a website, where you can make a reservation in advance. And they hardly speak English, so a phone number will be useless too.

Actually, you can find the accommodation when you arriving at the grassland. There are many guest houses with the size of yurt for you to choose. You can just choose one at that time.