Also look closely if that isn't it to see if the spring didn't break.
If it is just popped off, you can get it back on with the fender on, but be warned, it's a booger. You'll need the splash shield off and the door open, between the two openings it can be done. An extra set of hands would help immensely.
Vice grips and a small pry bar, you might get er on there.
Then you need a push nut to go over the end of that pin to keep it from popping off again. Think the little metal type cap that holds wheels onto kids toy with axles. It taps on and has little tangs on the inside that grip the pin.
