I plugged my USB stick in to the hub this evening - nothing. I plugged a few other devices into various ports on the hub - nothing.
So I pulled the hub apart (it is a cheap Chinese thing) and it looks, well, ok inside, nothing obviously wrong.
Then I plugged a few devices directly into the USB port on the back of the computer - still nothing. Tried a couple of USB port - still nothing.
Some USB devices were working (mouse, keyboard).
I rebooted.
Now everything is working again except the USB hub that is in pieces.