Sorry, but there's every reason for her to ignore you, Facebook means absolutely nothing. I've got friends on there I haven't seen for years and years, you sent a creepy message (mentioning the old picture is the creepy part). I'd ignore that too, there was probably another line or two that could've easily been seen as you trying to make things more than a Facebook friendship. Also, it's been four years, during college, she isn't the same girl you remember. Outside of becoming a big-time stalker and her getting a restraining order there's nothing you can do.
Well said, sir.
Brings me to a point about FB. ALL who are on FB have encountered friends from the past: "we were in Mrs. Smith 3rd grade class. . remember?"
I know 3rd grade is well off from a few years out of college, but the point remains. I had a chick friend me, pull the 3rd grade routine, and proceeded to seduce me via my wall, IM, and PM. It was creepy as ****!! I didn't mind a little back and forth - "remember elementary school," etc, etc. But she jumped right in.
She didn't friend me because we were friends in grade school. She friended me, saw I was single, and proceeded to stalk me. It got so bad, one time I was home for the weekend, posted on my wall that I was, and she would not leave me alone about catching up with her.
I made it CLEAR AS HELL when I got there. I called her bluff, walked in with a six-pack, one already drank before I got to the door, and acted like a total ass.
Why? You ask. Because ALL of your posts, IM, and PM's were indicative of her wanting a sex toy, etc, etc. SO gave her that. But when I got there, she pulled the cutesy "it's so good to see you. . we should grab dinner tomorrow," etc. I flat out looked at her, told her she was creepy, explained to her that when you tell a guy you'll - PG'ed - "rock his world," all to get him to your house so you can come off as a needy 30-year-old who wants a BF is ****ing insane. Then I left.
Why the long ass story, JS?
Because FB ca be easily misused, and appear, as a stalker tool. Be careful how you use it, what you say, and what you say to whomever. . in a relationship sense.