Error code 10 for arduino device driver
First of all, test if you even need a new driver. On Windows, the Arduino drivers for my Uno and my Mega were installed automatically by Windows. I'd advise to restart your computer, using the actual restart button, not manually shutting off and turning on... this is very important with Windows 8.1 and its Hybrid Boot default!!! A normal reboot doesn't fully reload all of the drivers. Next, open the Arduino IDE, and then see if you can successfully upload the "blink" example sketch.

If that doesn't work, let's try something else.

First of all, open up Device Manager and find your device:


  


It should be under the Ports (COM &amp; LPT) section. After that, right click and click on Properties.


  


Then, let's go to the Driver tab and click on Update Driver. Then, click on Search Online Automatically for this Driver.


  


First, try seeing if an automatic update finds any drivers capable. If not, I've found previously that there's sometimes a Reinstall or Fix button somewhere if the driver isn't working correctly.

In addition, you can also update it manually using Device Manager. Instead of clicking on Search Online Automatically for this Driver, click Browse My Computer Manually. For me, there was a Mega driver under the Let me pick from a list of compatible device drivers on my computer and there was a Mega driver for me (although I don't know if that's because I have it installed already).

You can also use that same menu to point it to the location of the installation of the Arduino IDE and it will search for any compatible drivers.

Rolling back the driver is another option if the Arduino IDE tried to install a faulty driver that somehow got corrupt over a working driver installed by the computer.

The last thing I would suggest trying as a last resort is using the Uninstall Driver button and then trying to reinstall the driver manually. I've never done this with an Arduino board, although there have been some times with other drivers that this has helped to remove the faulty driver.

If none of this works, it may be a faulty board.