How to Fix a USB Device That Isn't Recognized

Quick answer

When a USB device is not recognized, the cause is usually the port, the cable or a driver (the small program that lets your computer talk to the device). Start by unplugging it, restarting the computer, and plugging it straight into a different USB port with a known-good cable. If it still doesn’t show up, check Device Manager on Windows 11 or System Information on a Mac. This guide is for anyone with a flash drive, external hard drive, mouse, keyboard, phone or printer that the computer ignores or reports as unknown.

Before you start

Picture a student’s laptop that suddenly stops seeing the flash drive holding a class project. Before trying anything advanced, rule out the simple causes:

• Restart the computer. A restart clears many temporary USB glitches.
• Try another port. Plug the device directly into the computer, not through a hub, dock or keyboard port. On a desktop, the ports on the back connect more directly than the front ones.
• Try another cable. Many USB cables, especially cheap USB-C and phone cables, only carry power, not data. A device can light up or charge and still not be recognized.
• Give it power. Some external hard drives and printers need their own power adapter. Make sure it is plugged in and switched on.
• Test on another computer. If the device fails on two computers, the device or cable is the likely problem.

A note on safety: don’t plug in USB drives you found or received from strangers, since they can carry malware. And never install a “USB fixer” or driver-updating tool from an ad or pop-up. Drivers should come from Windows Update, macOS updates, or the device maker’s official support site.

If the drive holds important files, handle it gently and avoid formatting it, even if the computer asks. Formatting erases everything on it.

Check the device on your computer

These steps show whether the computer sees the device at all, and help it load the right driver.

Windows 11

1. Right-click the Start button and choose Device Manager.
2. Look for entries with a yellow warning triangle, or an Unknown device under Other devices. Also expand Universal Serial Bus controllers, and the category for your device (for example, Disk drives or Mice and other pointing devices).
3. Unplug the device and plug it back in while Device Manager is open. Watch for the list to refresh; that tells you which entry belongs to it.
4. Right-click the device’s entry and choose Update driver, then Search automatically for drivers.
5. If that doesn’t help, right-click the entry, choose Uninstall device, confirm, unplug the device, restart the computer, and plug it back in. Windows will try to set it up fresh. Only uninstall the entry for the device you are fixing.
6. Open Settings, then Windows Update, and install available updates. Look under Advanced options, then Optional updates, for driver updates in most versions.

For a flash drive or external drive that appears in Device Manager but not in File Explorer, right-click the Start button and choose Disk Management. If the drive is listed there, it may simply need a drive letter. Don’t choose any option that formats or deletes a volume unless the drive is empty or backed up.

macOS

1. Open the Apple menu, hold the Option key, and choose System Information.
2. In the sidebar, under Hardware, click USB. If your device appears in the list, the Mac sees it, and the problem is the software or the drive’s format.
3. For drives, open Disk Utility (in Applications, then Utilities). If the drive appears greyed out, select it and click Mount. You can also click First Aid to check it for errors.
4. On some newer Mac laptops, macOS asks whether to allow a new accessory to connect. If you clicked Don’t Allow, try unplugging and reconnecting the device to see the prompt again.
5. Install macOS updates from System Settings, then General, then Software Update, and install any software the device maker provides for Mac from its official site or the Mac App Store.

Fix device-specific problems

Some devices need a little extra:

1. Printers and scanners. They often need the maker’s software as well as a USB connection. See how to install or update a printer driver safely and how to add a printer to a Windows PC or Mac.
2. Phones and tablets. Unlock the phone and look for a prompt asking whether to trust the computer or which USB mode to use (for example, file transfer). Choose the option for transferring files.
3. USB-C and Thunderbolt. Not every USB-C port or cable supports data, video and charging. Check the computer maker’s documentation for what each port does, and try the cable that came with the device.
4. Wireless mice and keyboards with a USB receiver. Replace the batteries, and plug the receiver into a port that is close to where you use the device.
5. Drives formatted on another system. A drive used on a Mac may not open on Windows, and the other way round, depending on how it was formatted. Copy files off on the original computer before reformatting.

If this does not work

Try these next steps, easiest first:

• Check for dust or damage. Look into the port with a light. Unplug the computer first if you want to clean it, and use a gentle puff of air rather than poking metal objects in.
• Try a powered hub. If a bus-powered drive won’t start, a hub with its own power adapter can supply more power.
• Update the computer’s chipset and USB drivers. Get them from your computer maker’s official support page for your model, or through Windows Update.
• Check power settings on laptops. Some laptops reduce power to USB ports to save battery. Test while the laptop is plugged in.
• Look for a pattern. If no USB device works in any port, the problem is the computer; if one device fails everywhere, it is the device.

When to get professional help

Stop and contact the device maker, the computer maker or a qualified technician if:

• A port is loose, bent, burnt-looking or gets hot. Stop using it.
• The device smells of burning, or the computer shuts off when you plug it in.
• An external drive clicks, grinds or isn’t detected anywhere and holds files you need. Stop trying to use it, since repeated attempts can make recovery harder, and ask a data recovery professional.
• No USB port on the computer works after updates and a restart.

If someone calls or messages you offering to fix USB or driver problems over a remote connection, hang up. Real companies don’t cold-call about computer problems.

FAQ

Why does Windows say “USB device not recognized”?

Windows noticed something was plugged in but couldn’t identify it. The usual causes are a faulty cable, an unreliable port or hub, or a missing driver. Try another port and cable, restart, then check Device Manager.

Why does my USB drive light up but not show up?

It is getting power but the computer can’t read it. Check Disk Management on Windows or Disk Utility on a Mac. If the drive appears there but isn’t readable, it may use a format your computer doesn’t support or may be damaged.

Is it safe to uninstall a USB device in Device Manager?

Yes, for the device you’re fixing. Windows reinstalls it when you restart and plug it back in. Don’t uninstall entries you don’t recognize, especially controllers, unless you know what they are.

Do I need a driver for a flash drive or mouse?

Usually not. Windows and macOS include built-in drivers for most flash drives, keyboards and mice. Printers, scanners, some audio interfaces and specialist devices may need software from the maker’s official site.

Can a USB-C cable stop a device from being recognized?

Yes. Some USB-C cables only carry power, and some ports don’t support every feature. Try the cable that came with the device, and check which ports on your computer support data.