Macbook Pro not recognizing external hard drive

So I have never encountered this before and not sure what the appropraite steps to take are.

My external hard is failing to appear as a volume in finder (was off and on for a bit, but now it never does) it does appear in Disk Utility and says there is no EFI partiton (dont know what that means). Also, should note that within Disk Utility it used to show bothe the entire volume and then the whole partition below it and now what would be the partition is greyed out.

What should I do?