Another Fix for USB Not Working: the NVRAM Reset The USB ports on the MacBook should now work just fine, which you can confirm by connecting the USB device as usual and checking to be sure that it works – if it’s still not working, try another USB port, and try another USB device.

Boot the MacBook Pro / Air by hitting the power button as is typical.

Hold down Shift+Control+Option+Power concurrently for a few seconds, when the light on the power adapter blinks or changes colors you’ll know SMC reset is complete.

Shut down the Mac and connect the power cable.

For those with a MacBook, MacBook Pro, and MacBook Air, all you need to do is this: You can learn how to reset the SMC on all Macs here in our detailed tutorial. So, you’re confident a USB port is the problem and not the device itself? The first thing you should do is reset the Mac SMC, a simple process which is slightly different depending on the Mac hardware. The Solution to No-Cause Random USB Failure on a Mac: Resetting SMC

And yes, this can apply to any and all Macs, whether a MacBook Pro, MacBook Air, MacBook, iMac, Mac Mini, or Mac Pro. If multiple USB devices are not working on a particular port, or all ports, then it’s obviously less likely to be a device issue, and more likely to be related to the Mac itself. The easiest way to determine if the USB device itself is the problem versus the Mac USB port, is to try and use at least two different USB devices and switch their ports. This is particularly true with cheap low quality USB devices and cables.

First and foremost, keep in mind that sometimes a USB device itself can fail, which may have nothing to do with the Mac itself.

Usb cable for macbook air