How to retrieve the Windows 7 system CD drive that I have not seen?

First, in most cases, the CD-ROM drive of our computer is gone. It may be caused by the improper installation of the driver. We usually see the optical drive device in the device manager, but there will be an exclamation point on it. We only need to download and install the corresponding CD-ROM drive to solve.
Second, for the friend recently encountered, in the device management can not find the optical drive device, usually only two possibilities:
1, the optical drive is broken or the internal optical drive line is loose;
This situation, the author's friends can be excluded here, so the optical drive is good on the XP system, can not be replaced by a Win7 system optical drive is broken, can be used before, indicating that the internal connection is no problem.
2, Win7 opened ahci, CD-ROM drive is not compatible with ahci
>>.AHCI What is AHCI mode?
This situation should be encountered by the author's friend, by modifying the registry After that, it was solved. Here is a detailed introduction with everyone.
First use the combination shortcut Win + R to open the start dialog, then open the type: regedit command, click the OK button to open the registry editor.

Open Registry Editor Method
After entering the Registry Editor, expand:
HKEY_LOCAL_MACHINE--SYSTEM--CurrentControlSet--Control--Class--{4D36E965-E325-11CE- BFC1-08002BE10318}, as shown below:

As shown above, click on the registry value of {4D36E965-E325-11CE-BFC1-08002BE10318}, we find UpperFilters, LowerFilters in the right value of the right , delete it, as shown below:

Win7 CD-ROM drive is not seen
After the above steps are completed, we close the registry editor, and then restart the computer, after restarting the computer, usually enter the device management You can see the optical drive device.