Tell us the make and model of your brand name system, or if you have a generic desktop system, the make and model, or at least the model, of your mboard.
The model of a brand name system is usually on a label on the outside of the case,
or if it's a Dell system, go here to find your Service tag number, tell us what it is:
The model of a mboard in a a generic desktop system is usually printed in obvious larger characters on the surface of the mboard, often between the slots, or near the center of the mboard.
Some computers show a screen with the model number on it while booting the computer.
Are the USB controllers enabled in the motherboard's bios Setup ?
Do other USB devices work ?
It doesn't matter whether the USB port supports only USB 1.x specs - the flash drive (usb stick) should still be recognized - but you will get a "nag" message from the operating system "This device would work better if it was plugged into a port that supports USB 2.0 specs" or similar.
Troubleshooting USB device problems including for flash drives, external drives, memory cards.
See Response 1: