I have had the same Toshiba external hard drive for years and have never had any problems plugging and using from any machine, mac or pc. I recently had to reformat my hard drives and re-install windows 7, and ever since I have been unable to access my external from this machine. It still works fine on my laptop, and when I plug it in to my tower, it still recognizes that "External USB 3.0" has been plugged in and downloads the drivers. However, the drive appears neither under my computer nor disk management, nor diskpart -> list volume. It does show up in my device manager as USB mass storage but uninstalling the drivers and plugging it back in does nothing. Is there anything I can try before moving all my files off and formatting the drive, and will that even help? Thanks for reading.