So my friend Emily got me on the phone with her dad, who's some kind of computer consultant, and he told me how to do the disc repair thing. The good news is that my computer can still see the hard drive, which is better than I could say about my old PC a few years back that died and took all my data down with it. But it failed at "repairing disc permissions," so it's currently still not working. Hopefully tomorrow a Mac expert here at Barnard can help me out.
I think my first couple weeks here have become a bit of an example of Murphy's law... Augh. I just hope I don't lost my data... My computer's still so new! (Which I guess is a good thing since a lot of stuff is still on the computer at home.) I'm definitely getting an external hard drive once this is all over with, though.