HP SimpleSave not showing up

I have an HP SimpleSave external hard drive that I have been using to backup files with my MacBook Air (10.9.5). I never had any problems until one time I plugged it in and only the HP Launcher showed up in Finder, not the HP SimpleSave folder containing all of my files. I checked in my Disk Utility and the HP External HDD Media shows up with the HP SimpleSave drive below and indented, but the text for that it grayed out. I tried mounting it, but it says "Mount Failed" and "The disk “HP SimpleSave” could not be mounted. Try running First Aid on the disk and then retry mounting." After trying to verify the disk, it says the disk needs to be repaired. Repairing the disk gives me another error message that says "Disk Utility can’t repair this disk. Back up as many of your files as possible, reformat the disk, and restore your backed-up files." There is no way for me to access any files because it isn't showing up anywhere as being accessible.