maybe you have disabled the USB 2.0 controller in the BIOS of your motherboard.
Go in the BIOS:
Press del, f2 or f1, sometimes f12 at startup until you get the BIOS Screen.
Switch to advanced and look for USB Controller or something else. Look if your 2.0 controller is up and running. If not, enable it. So that`s all.
Then you can use your faster connection, again