Post: The drive letter is lost when a yellow exclamation mark appears in the Device Manager.

My computer suddenly couldn't find the optical drive and virtual drive in my computer! It's strange that the optical drive has never been used recently. I cannot find it today! If you cannot find the device, go to "Device Manager" and open "Device Manager". Then, you can see an exclamation point on the optical drive device. It's strange that you don't know which device to install. Program Problem. Then I try to reinstall it, and the result will not work. When you view the device properties, "the hardware device cannot be started in Windows because its configuration information (in the Registry) is incomplete or damaged. ( Code 19 )". After a great deal of effort, I searched online and finally found a solution. Now I am posting it to help you!

Warning improper use of "Registry Editor" can cause serious problems that may require reinstalling the operating system. Microsoft does not guarantee that it can solve problems caused by improper use of the Registry Editor. Use the Registry Editor at your own risk.

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To solve this problem, follow these steps:

1. Start "Registry Editor" (regedt32.exe ).
2. Find the upperfilters value under the following registry key:
HKEY_LOCAL_MACHINE/system/CurrentControlSet/control/class/{4d36e965-e325-11ce-bfc1-08002be10318}
3. On the editing menu, click Delete, and then click OK.
4. Find the value of lowerfilters under the same registry key:
HKEY_LOCAL_MACHINE/system/CurrentControlSet/control/class/{4d36e965-e325-11ce-bfc1-08002be10318}
5. On the editing menu, click Delete, and then click OK.
6. Exit "Registry Editor ". Note: After deleting the upperfilters value and lowerfilters value, if you notice that a specific program (such as CD recording software) has lost its function, you may need to reinstall the software. If the problem persists, consult the software supplier for help.
7. restart the computer.

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