well... I've been in a situation like this.... not really as bad, but similar.
and first of all: drop that "oh, I can't call her, what if i interrupt something?"-attitude to phone calls... If someone calls, it means someone want to tell you something... which generally is a good thing. If it is a bad point, the one being called can either deny the call, pick up and say that she's busy, or to be sure, you can ask yourself if you are interrupting something.
then, maybe she haven't read the mails... could be a possibility!
OR, she's depressed. I've been, and I didn't reply to emails, or messages or anything, even though I wanted... but every time I tried, nothing would come out from my head to write, so I just ignored it all.
Maybe she was in love with you (whether you knew it or not), and if your contact died for a while, it might have broken her heart. maybe making her depressed now.
Talking about this brings up emotions... I need to see my old friend soon! I've met her twice in two and a half year! and that's kinda bad, but when we meet, it's awesome!
To be honest, I was in love with her... and she went away to a university, which I also would've started. I didn't, and she dropped out. it was a 5 hour train ride one way between us, so we never got around meeting...
that was killing me. and then, she talked about all these new guys she started seeing, and sleeping with... and that killed me even more...
Maybe you've done something like that? got a girlfriend, told her anything she didn't want to know....
and for her birthday... Buy her a flower... not some plant.. but a bouquet... not 20 red roses... cause... that's what lovers do... but some nice beautiful ones... show up at her work, step right in and make a scene
that's something I think she'll enjoy. Co-workers will start asking questions (when you've leaved) , and she'll probably start remembering more and more good things and good times you've had... and finally melt away.
Ah, there.. hope it wasn't too much to read!
and that some of it can be useful! (but Please try anything of it, and don't come with excuses like "maybe I'll disturb"...)