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USB Port Not Working? Troubleshooting for Windows and Mac
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USB Port Not Working? Troubleshooting for Windows and Mac

Computers • 5 min read

A USB port that stops recognizing drives, keyboards, mice, or audio devices can be caused by a bad cable, insufficient power, a disabled controller, a driver problem, or physical damage. Work through the shared tests before moving to Windows- or Mac-specific fixes. For a related guide, see iCloud Storage Is Full? How to Free Space on iPhone, iPad, and Mac.

First, determine whether the port or device is faulty

Use a known-good flash drive for the quickest diagnosis, then test your original USB device as needed.

  1. Try the flash drive in every USB port. If it works in another computer but not this one, continue troubleshooting the computer.
  2. Test the original device and cable on another computer. If they fail there too, replace the cable or repair the device. If they work, the connected hardware is probably fine.
  3. Remove hubs and docks. Connect the device directly to the computer. A powered hub can confirm that the port lacks enough power for an external drive or other high-power accessory.
  4. Compare the results. One dead port suggests port damage. Several dead ports suggest a controller, software, firmware, or motherboard problem.

With USB-C, use a data-capable cable and test every available port. Do not force the connector.

Try these quick fixes first

  1. Restart the computer. Unplug the USB device and other nonessential USB accessories, restart Windows or Mac, and reconnect one device at a time.
  2. Inspect the port. Use a light to check for bent contacts, a loose metal shell, or packed debris. Do not insert metal tools or use liquid. Stop if the port is visibly damaged.
  3. Power-cycle the computer. On Windows, shut down, unplug power for 30 seconds, reconnect it, and start again. On Mac, shut down, unplug power and accessories for 30 seconds, connect power only, wait 30 seconds, then turn it on.
  4. Reduce power demand. Connect desktops to rear motherboard ports when possible, avoid unpowered front-panel ports, and use a powered hub for an external drive.

Fix a USB port not working on Windows

Update or reinstall the USB controller

  1. Press Win + X and choose Device Manager. Expand USB controllers.
  2. If a controller has a yellow warning icon, right-click it, select Update driver, and choose Search automatically for drivers. Restart afterward.
  3. If entries are missing or the problem continues, right-click a USB Root Hub or USB xHCI Compliant Host Controller, select Uninstall device, and restart. Do not choose the option to delete the driver software.
  4. If the controller entries remain missing or errors repeat, download the latest chipset or USB driver from the PC or motherboard maker. Avoid generic driver-download tools.

Disable Windows USB power saving

  1. Open Control Panel > Hardware and Sound > Power Options. Choose Change plan settings, then Change advanced power settings.
  2. Expand USB settings > USB selective suspend setting and set it to Off.
  3. In Device Manager, open USB Root Hub > Properties > Power Management, clear Allow the computer to turn off this device to save power, and select Apply.

Install Windows updates and check firmware settings

  1. Go to Settings > Windows Update > Check for updates. Install available updates and restart the computer.
  2. Restart and press the firmware setup key shown during startup, commonly F2, Delete, Esc, or F10. Under USB Configuration, make sure the controller and ports are enabled. Save and exit; labels vary by manufacturer.

If the drive appears but will not open

Press Win + X and open Disk Management. If the drive has no letter, right-click its partition, choose Change Drive Letter and Paths, and add one. If Windows asks to initialize or format the drive, cancel because those actions can erase data. If the drive does not appear here, continue troubleshooting the port.

Fix a USB port not working on Mac

Check whether macOS detects the device

  1. Click the Apple menu > About This Mac > More Info > System Report.
  2. Under Hardware, select USB or USB4, then look for the connected peripheral under the bus.
  3. If the device appears, the port is detecting it and the problem may involve the cable, storage, or permissions. If several known-good devices do not appear on any port, the controller or hardware is more likely at fault.

Use a data-capable cable and remove intermediate hardware

  1. Try another known-good USB-A or USB-C cable. Some USB-C cables support charging only and cannot transfer data.
  2. Connect Mac directly, remove hubs and docks, and test every port.
  3. For an external drive, try a powered dock or hub. If it works only through powered hardware, the Mac port may not supply enough current.

Reset power management

  • Apple silicon Mac: Shut down and unplug power and accessories for 30 seconds. Reconnect power, wait 30 seconds, then start.
  • Intel Mac with a T2 chip: Shut down. Hold left Control + left Option + right Shift for 7 seconds. Add the power button and hold everything for 7 more seconds. Release, wait 5 seconds, then start.
  • Other Intel Mac: Shut down. Hold left Control + left Option + right Shift for 7 seconds and release. Hold those keys again for 7 seconds, then press and hold power while continuing to hold the first three keys. Release, wait 5 seconds, and start.

Reset NVRAM on Intel Macs only

  1. Shut down, start the Mac, and immediately hold Option-Command-P-R for about 20 seconds.
  2. Release after the second restart. On some T2 models, continue until the Apple logo appears and disappears twice.
  3. Reconnect the USB device and test it again.

This reset may change the startup disk, clock, time zone, and volume. Apple silicon Macs do not use this reset.

What your test results mean

  • One port fails while others work: The failed port may have physical damage or a port-specific fault.
  • All ports fail with multiple devices and cables: Check the controller, firmware, operating system, or motherboard.
  • The device works directly but not through a hub: The hub, cable, or power requirement is likely the problem.
  • Storage appears in Disk Management or System Information but will not mount: The port may be working; the drive or file system may need repair or backup.

When to seek repair

Stop troubleshooting and have the computer inspected if the metal shell is loose, the contacts are bent, debris will not come out gently, the port sparks or becomes hot, or liquid damage occurred. If several ports still fail after the tests above, the USB controller or motherboard may need service.

Bottom line

Start by swapping the cable, device, port, and hub. On Windows, update or reinstall the USB controller and disable power saving. On Mac, confirm detection in System Information and reset power management. Visible damage or failure across multiple ports usually calls for professional repair.