Why do USB ports stop randomly working?

Try reinstalling the drivers!

'brand new' means it is under warranty or return for failure policy.  send that thing back

I've never personally experienced a USB port just randomly stop working.  The PC I'm using right now, I built myself back in February 2015.  I purchased every single part, the case, CPU, mobo, memory, GPU, PSU, monitor, keyboard, mouse.  Well anyway this PC gets a lot of use.  But in all of the 5 years that I've had this PC, not one USB port has failed on me.

On the front of the case are two, USB 3 ports, and in the back are two, USB 3 ports and four, USB 2 ports.  I have every USB port used in the back, no problems.  And even with using the slots upfront, no problems there either.

It sounds like bad luck.  A relative of mine bought their mobo, case, PSU, GPU, the people at the store, who are IT certified, even helped them pick all the parts they'd need.  No matter what they did, it wouldn't work.  Took it to the store after a couple of months for them to figure out.

They ended up going through three motherboards, before they could get one that was functional.  So it was just bad luck, they ran into a bad mobo.  I got lucky with this PC because it started right up when I pressed power, and it was my first and probably last time I'll build a PC.  Too much stress and anxiety.