# Windows can't find external USB drives



## villandra (Nov 20, 2006)

My computer suddenly can't find my two external usb hard drives. It doesn't matter which USB plug they are plugged into. They are plugged directly into USB plugs on the computer and not into a card or hub. The two drives are not showing in my disk manager, nor under disks or memory in my device manager. I checked for IRC conflicts and can't find any.

The only thing I am finding is that under nonplugandplay drivers there are yellow exclamation points next to !Pmem and !MCSTRM. The drivers are apparently not there. I don't know what they are, and all I can find out is that sometimes they are really malware and they don't need to be running. I don't think this is connected to my problem with the hard drives.

I want to back up my files, so I need the external drives working. 

On line I keep finding directions to look for the external drives in the disk manager or the device manager, and what to do if I find them, but it never says what to do if I DON'T find them. What do I do if I don't find them? 

One of the two drives runs noisily, but they were formerly both working. The plugs appear to be in good shape, and yes, I made sure they are all plugged in. I have unplugged them and plugged them back in. I have tried rebooting the computer. 

The computer is not having trouble finding flash drives plugged into the same USB plugs.


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## makinu1der2 (Jan 1, 2008)

Are the drives recognized on another PC?


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## Amounderness (Nov 29, 2011)

For some reason some Windows systems, even Win7 sometimes can't see a USB that XP can see. Or you take a USB to a client's and it won't open but it was just fine back at your office. Sometimes, whatever the supplier says the USB isn't totally USB2 compliant. If you plug a USB1 hub in and then the USB into that it works just fine.


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## spunk.funk (May 13, 2010)

With the drives attached, go to Start/Run and type *devmgmt.msc* and press enter, In the Device Manager are there any devices with yellow marks? Or under *U*niversal *S*erial* B*us Controllers is there an *Unknown Device*? If so, right click and *Uninstall* it. Now pull the USB cables out of the _computer end_ for the drives and _restart _the computer. Once the computer has restarted, make sure the drives power adapters are the correct ones that came with the drive, this would cause this problem. If so, then make sure that the power adapter is plugged directly into the Wall _not _into a surge protector or extension cord, which would diminishes the power. Now plug one drive into the _Back _USB port of the computer and not the front and not through a hub as this also diminishes power. If that works, try the other drive. If either do not work try the steps above again or on another computer.


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