Phantom USB

I have a USB that's formatted for Windows. I need to reformat it for my Mac but it won't show up ANYWHERE. I'm not a novice so I've tried out all the common fixes but it literally won't even show up in Disk Utility. The USB itself is fine as it works on other computers. Also my USB ports are completely fine too. Does anybody have any insight?

Thanks.

Formatted for Windows as FAT32 or NTFS? If the former, then it should show up in OS X, if the latter, then it won't show up until you install the NTFS support in OS X. If you intend to reformat the USB drive for OS X anyway, then plug it into a Windows machine where it is seen and format it as a regular FAT32 drive, then plug in into the your Mac and reformat and go..