I am level10 now i can't get EXP
I kill monster can't obtain EXP
I miss some mission or quest?
How should i do now ?

I don't know how should i do now.

Check the monsters you are killing. Some of them are probably checking as "Too weak" and this means you can no longer get Experience Points from them. Considering moving further from you starting town to find monsters that stronger. You can also join up and team up with other players at level 12+ to get some experience. You can do so by going to the Party menu and using " Seeking Party" to let others know you are interested.

Also make sure the character you’re using is either your “main” or your “alt”. Your mule can’t go past level 10.

I wish the server would actually enforce that. That way people who don't read the rules wouldn't get pissed off when it's deleted or deleveled to 1.