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My laptop has two USB ports, but one is broken, so I use a USB hub in the other good USB port. In that USB hub, I use a mouse and keyboard. Suddenly, that USB port doesn't detect the mouse and the keyboard (even with the light of the hub is on), and the only solution that I found is restarting the laptop. But just some minutes and the keyboard and mouse goes undetected again...

Is there some method, software, etc. to "restart/repair" the USB port without restarting the PC?

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4 Answers

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If you have no power supply added to the USB hub, check if that helps. May be the laptop has not enough power on the USB, some older laptops had not the full 500mA.

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Interesting! How I can check that voltage? – Click Ok Dec 18 '09 at 0:09
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Powering a mouse and a keyboard via the USB port should not be a problem. I really wouldn't worry about that. – Paul Lammertsma Dec 18 '09 at 10:56
Some computers show the voltage in their driver settings. Regarding the power consumption - or the problem - try finding the combination that brings trouble by using only one of the components, e.g. only mouse without the hub and the keyboard and if that works use only the keyboard and so on. Alternatively you can check if you have a power supply that fits to the hub, e.g. on my hub I the disk did not work and I found a 5V power supply that had the same +- combination and plug and now it works. Again: My old Dell Laptop produced only 300-400 mA. – Thomas Dec 18 '09 at 11:22
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up vote 3 down vote

None of the answers quite answer the title question.

How to “restart/repair” a USB port?

There are three ways to "restart" a particular USB port:

  1. Reboot the computer. Or ...
  2. Unplug, then re-plug, the physical device connected to the port. Or ...
  3. Disable, then re-enable, the USB Root Hub device that the port is attached to.

In Windows you'd do (3) through the Device Manager or via the devcon.exe utility.

The reason these are the only methods is due to the USB handshaking protocol, which is initiated by the USB device when it's plugged in, not by the controller. This causes problems like being unable to remount a USB flash drive after you've Safely Removed it. But cycling the USB Root Hub device causes all the devices attached to that hub to reinitialize themselves. (The unfortunate side effect is that it causes all devices attached to that hub to reinitialize themselves, which could be problematic if you have other devices on that hub which are in use.)

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up vote 2 down vote

You should look at NIRSOFT's USB Device view (http://www.nirsoft.net/utils/usb%5Fdevices%5Fview.html). I have used this to fix a system that had a disconnected U3 USB drive still mounted preventing anything else in the port being recognized.

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up vote 2 down vote

Can you check your event viewer for any obvious errors in the application or system logs?

I don't know what the problem is at this point, but you should inspect the drivers installed. Are they Microsoft default input drivers or custom drivers? You might need to reinstall the drivers. It could be possible that the instance of the drivers is failing.

Also try inspecting the drivers after plugging in the device. You might see a resource conflict or some other warning in Device Manager.

Since the problem is occurring for two different devices, I think it's less likely a hardware failure on the mouse or keyboard.

The failure is definitely on your laptop.

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