Whether you’re plugging in a USB drive, a headset, a printer, trying to sync your MP3 player, or even your smartphone, you expect your USB devices to just work the moment you plug them in. That’s the beauty and simplicity of USB, or Universal Serial Bus, which is designed to let you connect and disconnect devices as you please, often on both Windows and Mac computers, without a lot of fuss.

When your USB ports suddenly stop working, the problem can always be traced back to a hardware or software error. Some of these problems are the same for both Windows and Mac, while others are unique to only one of the two.

Restart your computer. Sometimes you get lucky and the simplest solution solves the biggest problems.

If rebooting doesn't help, it's best to move on to more complicated solutions.