You didn't reveal if you did a full reboot.
All of my USB ports suddenly stopped working. I left my computer on sleep for a few days and when I came back my keyboard and mouse LED's weren't on. I tried different ports and none of them worked. When I tried replugging in the USB wires that go into the mobo, my mouse LED would flash for an instant and then go dead. Is there perhaps some type of problem with too much current going through the USB ports? My mobo is fairly new with not much use on it. I believe its a MSI Z97 gaming 3 or 5 motherboard.