Acomdata External Hard Drive blue light constantly.... I am having a problem with my external hard

Question

I am having a problem with my external hard drive. I was in the middle of editing in lightroom last night and all of my pictures suddenly became missing and invalid. I look over and the blue light is flashing rapidly on the Acomdata Hard drive and then I go to explorer and it is no longer in my directory. I cannot get it in my directory no matter what I do. Please help me as I have several jobs that are on here that I need to access.