My daughter cries more often recently too. I don't know what happen but i can see she is moody. :(
When she cries, i try to tell her it is useless and can't help anything.
We also should ignore them if they cry for unreasonable requests, behaviour and so on.
However, children seem not to be able to control crying or not sometimes.
my daughter is moody once she is not able to do somethings, just like writing the words nicely, cutting the paper well, putting the lego into the correct places, losing in the game... :(