I have 2 boards and loaded and ran test code a couple of weeks ago.
Today I get an error on Windows 10 USB Device not detected. ( The loaded code is running OK - nice blinky LEDs!)
I have swapped boards ,swapped ports , double clicked reset rebooted but still no board detected.
I also re installed the USB driver.
Any suggestions?
Ted
Hi Ted.
Thanks for posting in the forums! 
If you double tap the reset button, does that get you a COM port in windows? That should also make the board pop up as a USB drive as well.
I have tried again with both boards.
Double tap on one board give bright green NeoPixel LED and USB not recognised.
Strangely double tap on the second board has a not so bright Green Neo pixel and is now recognised!
Further swapping kit around led me to a conclusion that one of the USB cables i was using was the weak link.
One USB cable gave me a recognised device a second cable did not. Even though the second cable did work with an Adafruit M0 board.
Is there something in the Sparkfun code that is unduly influenced by a ‘poor’ cable? USB power request perhaps?
I hope this comment helps others.
Ted
Hi Ted
Is there something in the Sparkfun code that is unduly influenced by a ‘poor’ cable? USB power request perhaps?
Not that I know of, but I’ve experienced the same thing with multiple SparkFun and non SparkFun USB products. I don’t have any evidence to back this up, but I suspect that the speed a product runs at (over USB) or the enumeration process for specific firmware could be exposing weak cables that work fine on lower speed or less demanding devices. I’ve also noticed that short cables (6" long) can sometimes have problems with some devices as well.
Power could be a cause as well, but I can’t think of anything offhand that we carry that would need excessive amounts of power. Things that need a lot of current will often have problems with cheap (thin) USB cables since a lot of power is lost in the wire due to I²R losses in tiny cables.