Flash Drive Not Appearing on desktop or in disk utility

When I insert a flash drive into my USB port on my mac desktop, it doesn't show up on the desktop. It's also not appearing when I open a new finder window (on the left hand side under devices) or in disk utility.

A light comes on on the usb flash drive, so I think it's an issue with my computer?! I've tried several usb external drives as well.

My cd/dvd isn't working either.

Any suggestions would help!

Thanks!