USB has decided to no longer work right...

Most (4/6) of my USB ports no longer work.
When I boot windows it says that there is a USB device connected when there isn't. This happens when a device (keyboard, mouse, gamepad) is plugged into one of the non-working ports.
In my Device Manager, whenever a device is plugged into a non-working port, it will flash a "USB Device" then disappear, then reappear, then disappear, repeating on and on...
I was wondering how I might go about fixing this.

>>5
To get to safe mode without a keyboard, pull the plug on windows while it is booting (before you get to the login prompt/the desktop). Then plug the power cord back in, and boot up again. It should give you a menu to access safe mode from automatically.