Ok, currently in school now replying to this thread. 
Alright dude, there is one thing I wished to comment about your
case one. Firstly, when you helped her get through her difficult
times, DOESN'T mean that she has to be there for you when you are
undergoing the same thing. Helping someone is volunteering without
expecting anything in return. If she doesn't want to contact you,
she has her own reason. Probably in my opinon she wants to calm
herself down and ponder over herself for a moment. 
Its good to lend a helping hand, but its criticial
to understand when someone needs some time for his/her own.
Now onto the next case; your second case doesn't involve you
personally, its more about her. I mean if you take it so personally
about she not knowing who are you, then it will be personal.
Frankly speaking, if I were you, I wouldn't think so much.
Afterall, even though you have fancy for her - in status, you are
just her casual friend.
P.S: Its good to take steps in trying to understand and get to know
her better before committing yourself into thinking that she is a
potential. Many a times, impression alone isn't a gauge for what
could be good & suitable for you.
Cheers
