I am lucky that I was able to find some great Mac USB recovery options when I did. I cannot tell you how useful it is to be able to restore important files that were on your USB by using a simple program on your Mac. I used a lot of trials, free programs, and even a professional recovery to restore some files to no avail. After nearly giving up, I found one that I could pay for and download. Then, all I had to do was connect my USB, select it in the program, and check which files I wanted it to recover. It did and recovered the files I needed on it.
The Phat Photographer