ARGHHH what do I do!!

Apparently I bombed a Chemistry test, but it wasn't hard to me.  I looked at my grade today and it dropped an entire letter!  Ahh, this is killing me.  Even if I didn't study, I would've done better than my grade said.  I'm so confused and worried right now; my nails are basically gone because I bite them so much LOL ...

Ahhhhhh if my mom sees my grade, I just know what she's going to say, and it's not gonna be pretty at all  :////////

Help!!  What do I do??????  *sobs for eternity*

♥ Emmy