|Your symptoms indicate that either|
- you're plugging it into a USB port it can't work properly with e.g. it may not work properly in a port in an external hub, or in a port on the front of a desktop case,
- or your flash drive's USB plug or the USB port is damaged.
Plug it into a different USB por - e,g. a port built into a laptop's case, or a port built into the mboard on the back of the computer on a desktop case.
Lots of info about that -
See response 1:
A lot less likely, but certainly possible - check for physical damage.
Inspect the USB plug on the flash drive, and the USB port you're pluggnig it into, to make sure that they're not damaged
- the (male) USB plug should be snug, not loose, in the (female) USB port. The metal of the plug should not be bent inwards, and the metal of the outer shell of the USB port you plug it into should not be bent or stretched outwards
- the plastic blocking plug in the USB plug and in the USB port that prevents you from plugging in the USB device upside down in the port should be in both sides and not be loose
- the 4 metal contacts inside the plug and the port should not be bent out of place.