Where do I find USB controller driver for Dell 435T  

My Dell XPS 9000 435T PC suddenly cannot read SD cards.
The Device manager has a yellow exclamation the Other Devices>USB Controller
When I R Click on the USB controller I get "no driver find a driver with two options

1 to search on my computer with a browse window (wher would I find the needed driver)
2 choose from a list of manufacturers and model (there is no info on the USB controller manufacturer)
3 third choice is search the internet for the driver (which goes on endlessly when selected)

How can I solve the problem of getting the USB driver I need to recognized my SD card??

I'm not sure a card reader would show up as a USB controller, so I'm not sure if you have one problem or two. Maybe it does, but just to be sure have you scanned through the rest of the Device Manager tree to make sure the card reader isn't showing up somewhere else, such as perhaps under "Disk drives" or "Storage"?

At any rate, the M435T card reader driver is available on Dell's website. You might also want to look inside and check/reseat the connecting cable.