Hello SachaMusic
When you connect to your computer, a box should come up like Hardware now connected, if the message “it is safe to remove hardware” comes up then your keyboard has been disconnected from the computer, and so will not work.
Try connecting to a different USB port; make sure you disconnect your keyboard from the computer, before unplugging the USB lead, try restarting your computer with the USB lead left plugged in.
Hope this helps.

Bill