|USB devices may not work correcly when they're connected to certain USB ports e.g. ports in a hub or on the front of a desktop case. If you have a desktop computer, you may have an IRQ sharing problem you need to fix. |
See response 3 in this:
Also - if you are using a USB extension cable, some of them have inadequate wiring and will not work properly with some USB devices.
External drives require a lot of power, and they won't work properly in all possible USB ports you can plug them into.
See response 1 in this:
When you plug in or unplug a USB device, if you have your sound on and the volume is high enough, you hear one sound for when a device is plugged in, another similar sound for when it's unplugged. Your having heard the sound doesn't necessarily indicate the Safely Remove Hardware icon should appear.
Only certain USB devices make the Safely Remove Hardware icon appear in your taskbar - e.g. printers, scanners, multifunction printer/scanner/etc. devices, flash drives, memory cards, external drives, sometimes cameras - plugging in mice or keyboards or some other USB devices that no data can be stored on will NOT make it appear. In XP, 2000, ME, and 9x, it's a grey rectangle with a bright green arrow on it. In Vista and Windows 7 it's a mid green circle with a white checkmark on it. That icon may be hidden if it's already there - you may need to click on the < at the left end of the icons in the taskbar to reveal it.
A new external drive, or a new hard drive in an external enclosure, or a hard drive in an external enclosure that has had the partition(s) deleted on it, will NOT show up as a drive letter in My Computer or Windows Explorer, or as a drive letter when you click on the Safely Remove Hardware icon if it's there, until the drive has been software partitioned and formatted using something Windows recognizes. In 2000, XP, Vista, and Windows 7, you can do that in Disk Management.
Similarly, if a memory card has had it's partition(s) deleted, or if it's been software partitioned and formatted using something Windows doesn't recognize (e.g. done in a camera), it will NOT show up as a drive letter in My Computer or Windows Explorer, or as a drive letter when you click on the Safely Remove Hardware icon if it's there.
If the USB device has data on it that you were able to access previously and you can't access the drive or the data on it now, if it's plugged into a USB port it should work fine with according to the info above, it is quite likely you have NOT been clicking on the Safely Remove Hardware icon in your taskbar and choosing to STOP accessing the drive letter for the device ALL the time when you have been unplugging it while Windows is running, and the data on the device was damaged because you were not doing that at least some of the time.
In that case, the drive letter for the device will probably not show up in My Computer or Windows Explorer, and it won't show up when you click the Safely Remove Hardware icon when it is present.
If it's an external drive, the hard drive model that's inside the drive shows up in Device Manager if there is nothing wrong with the hard drive or the external enclosure's circuits or its connection via USB, but it may not show up in Disk Management.
If it's an external drive or a flash drive or a memory card, the external enclosure's circuits or the flash drive or the memory card show up as a mass storage device listed under USB controllers in Device Manager, if they are being recognized correctly and they are plugged into a USB port they can work with.
If you can't access the drive or the data on it now, if you could previously, you need to use a program that will attempt to repair the damaged data that is preventing you from accessing the data on the drive on the device normally.
Testdisk - get the Stable version:
PC Inspector (freeware)
Zero assumption Recovery
The demo is limited
It will only recover 'up to' four folders per run
But you can make multiple runs
Really good, but you have to pay for it.