I.G.
Please don't try to take this personally or make it an emotional issue. It is completely normal for children in that age range to become picky. It's a developmental step and that will come and go in phases over the next years.
It's funny, because my pediatrician had warned my about it at one of our checkups, and I though "No way" because my daughter was such a healthy eater - but sure enough a couple of weeks later she suddenly would not touch anything green any more.
Just keep offering healthy food and I promise she will go back to eating them! I currently do the following (my child is a little older): I offer the vegetables raw as well as cooked (she prefers some uncooked), I don't mix her food together, but put in on the plate seperately (helps to an extent and she doesn't spend more time picking than eating) and if she won't eat what is offered she may have whole wheat bread (we usually serve some with dinner) instead. I don't cook extra meals for her.
Oh - and get rid of the junk food. If there is none in the house, she won't starve herself!