Unable to read external hard drive after BSOD

Hi, I recently wiped my macbook and reinstalled mac os and windows bootcamp on it. I was trying to backup my windows side on my external hd when my mb crashed w the bsod and after restarting, my external hard drive can't be read. I get the message that i need to reformat it before i can use it. Problem is, before wiping my macbook, I transferred all my project work and photos and other important files into my hard drive so its my only backup. I'm only a student, so is there anything I can do without paying a bomb for data recovery services? Thanks.