Cochleah

Hello everyone, I'm attempting to apply to graduate school in the fall and I've reached a bit of a predicament. I've been working as an Audiology Assistant for a few years, and I've been out of school for a while. The requirements for the three letters of recommendation state they must come from a professor who can vouch for my abilities as a student. However, I'm 100% sure none of my old professors remember me. How do I go about obtaining quality letters of rec. from professors who don't have the time or are not willing to do so? This is literally the last piece of the puzzle and any insights you may have would be appreciated. Thanks!