W 7 First, please disconnect all USB devices and then perform the following steps:
Click "Start" button, type "devmgmt.msc" (without quotation marks) in the "Search" bar and press "Enter". Click "Continue" if necessary.
In Device Manager, double click to expand "Universal Serial Bus controllers", right click on the Host Controller, click "Uninstall" and click "OK".
Repeat the step 2 to uninstall all items under "Universal Serial Bus controllers".
Then, restart your computer and Windows 7 will reinstall all USB controllers automatically. Click start control panel scroll to folder options view place a tick in show hidden files folders and drives
this may vary depending on your operating system for XP or earlier click start right click on computer select properties device manager scroll down universal serial bus controllers you could see a yellow question / exclamation mark? ! or a red X you will need to update/reinstall drivers right click to reinstall drivers if you can see your usb drive but its not working ports (com&lpt) right click update driver if this fails to fix the problem Check the USB leads that attach to the motherboard usually red white green black make sure they are securely seated and have no dust build up on them dust will cause static and a lot of unforeseen problems to a computer and its parts
Access an Inaccessible Drive
b> You can gain access to a working hard drive that is inaccessible when the system starts and assign it a drive letter under the Windows Explorer interface. Or, you can import foreign disks into Windows or create a partition and format them. You can scan a drive for bad sectors or lost clusters and repair the system files to allow access to a corrupted drive. In short, you can utilize the drives as they were intended to be used by completing some operating-system configuration steps that are occasionally required for some drive installations.
Click "Start" (the Windows Orb) and "Computer" to access the Windows Explorer screen. Right-click on the inaccessible drive and choose "Properties" from the context menu. Click the "Tools" tab and click "Check Now" under the Error-Checking section. Select both check boxes to allow the system to automatically fix file-system errors and to scan for and attempt recovery of bad sectors. Allow the system to run the scan the next time the system is booted. Restart the computer to complete the scan and check for access after the scan completes. Click "Start" (Windows Orb) and "Computer" to access the Windows Explorer screen. Right-click on the inaccessible drive and choose "Properties" from the context menu. Click the "Security" tab and click "Edit" to change permissions for the drive. Click "Users" from the Group or User Names section. Check the "Allow" box for full control and check for access after the settings are saved. Click "Start" and "Control Panel" and then click "Administrative Tools" and double-click "Computer Management" to launch the utility. Click "Disk Management" to display a list of all detected drives in the system. Right-click in the left column of the inaccessible drive and click "Import Foreign Disk" to allow the system to convert the disk signature to a local disk. Check for access after the settings are saved. Click "Start" and "Control Panel" and then click "Administrative Tools" and double-click "Computer Management" to launch the utility. Click "Disk Management" to display a list of all detected drives in the system. Right-click in the right column of the inaccessible disk and choose "Change Drive Letters and Path." If no letter exists, click "Add" and assign a drive letter from the list of available letters. If a drive letter is listed, click "Change" and select a new letter to eliminate any conflicts with other devices in the system. Check for access after these settings are in place, which may require a restart of the system. Click "Start" and "Control Panel" and then click "Administrative Tools" and double-click "Computer Management" to launch the utility. Click "Disk Management" to display a list of all detected drives in the system. Right-click in the right column of the inaccessible disk and choose "New Simple Volume" to create a partition and format it for use. Click "Next" when the New Simple Volume Wizard appears. Click "Next" to accept the maximum for the drive. Click "Next" to accept the suggested drive letter assignment. Click "Next" to format the volume with the suggested defaults or change them if desired. Click "Finish" to format the drive and make it accessible to the operating system. Restore a Drive That Is Not Accessible
b> Microsoft Windows operating systems support a large number of file system formats including FAT12, FAT16, FAT32 and NTFS. Hard drives are typically formatted with either FAT32 or NTFS, both of which can be used for years without issues. Damage can occur to the file system through a sudden power outage, malicious software or lack of maintenance, rendering the drive unreadable or inaccessible. Run the Chkdsk utility in Windows to resolve file system corruption and restore access to the hard drive.
Select the "Start" or "Globe" button and then click "Programs." Click "Accessories" and then right-click the command line icon in the menu that appears. Click "Run as Administrator" in the drop down menu that appears. The command prompt will display. Enter "chkdsk C: /F" substituting the "C:" with the letter assigned to the drive that cannot be accessed, and then tap the "Enter" key. Enter "Y" and tap the "Enter" key if a message appears that states "Would you like to schedule this volume to be checked the next time the system restarts? (Y/N)." Let the disk scan run and fix the drive, or if the scan does not start, reboot and let the scan run and repair the drive. http://technet.microsoft.com/en-us/library/cc730714%28WS.10%29.aspx