Reading through this thread takes a lot of time, but there is a lot of good info here. In addition, i would say that most of the tricks and ways to repair usb have been mentioned here in this thread.
The most popular one being technophobe's post, here:
https://www.techspot.com/vb/topic23630.html
The bottom line is that often if you unhook all your usb hardware, remove all your usb drivers, let the pc sit for a while, turned off, quite a while sometimes, like a half hour, then boot up and re-install your drivers, that will take care of almost all issues.
There is one item i see, though, that hasnt been mentioned. I have a few pcs and one pc i have i have trouble quite often when i plug a usb2 hard drive into the usb2 ports on the front of the pc. Yet when the same drive is plugged into the back of the pc then all is well. Now its the same usb2, direct to the mobo, so dont ask me why but it works fine in the back so i leave it there and plug other items in the front, thats how weird usb can be.
Another thing that i dont think i have seen mentioned here, and if it has then please forgive, but sometimes it just pays to install a usb2 pci card. Sometimes that works better than using the usb on the mobo.
And i have even see usb problems disappear by turning the pc off, unhooking the pc from the wall or wherever its main cord is, letting the pc sit for a while and then push the case on\off button in and hold it in for a few minutes. What that does is clear the motherboard of any electrical charges in it and somehow i have seen that help with usb and other issues.