You might try plugging it into a different USB port.
However, try the following:
Click on the start icon on the bottom left
RIGHT click on “computer” in the right hand column
LEFT click “manage”
left click “Disk Management”
wait a minute to see if the disk shows up in the top menu, it will say something “healthy” and/or “active partition”. If it says something other than that, you may have to format it by RIGHT clicking and then Left clicking “format”