If you plug your usb drive into a working usb slot, then it should show up in the start>computer>Devices with removable storage.
This is assuming your working with windows 7.
I would make sure the usb slot your using is working, and if it is, I would check
control panel>hardware and sound>devices and printers, there you should see everything that is plugged in to your computer, printers, mouse, keyboard etc
Check to see if it shows up in there.
Also:
When you plug and unplug that usb in, does your computer make a noise, like dun dun?