usb mass storage problem

usb mass storagenot detecting , usb pen drive not working , usb hard disk not working.
to solve the above problem may be occur due to  error in windows registry .
1. click on Start
2. click on Run
[to bypass the step 1 & 2 press and hold  Winkey and press r]
4. type -> regedit then and click OK.
4. find the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E980-E325-11CE-BFC1-08002BE10318}
5. Click on Edit menu, and select Delete and click OK.
6. find the  following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E967-E325-11CE-BFC1-08002BE10318}
7. Click on Edit menu, and select Delete and click OK.
8. Exit Registry Editor
9. restart your system.
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