When accessing Device Manager there may be hidden devices that are not displayed.

This trick forces all devices to be displayed.

You must make the following changes to the Windows registry.

CAUTION: We strongly recommend that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.

Click on START > RUN and type regedit
Then click on Ok button.

The Registry Editor, will be appeared.
In the left pane of the Registry Editor, navigate to the following subkey (making double click on each registry key):

HKEY_LOCAL_MACHINE
SYSTEM
CurrentControlSet
Control
Session Manager
Environment

Now, in the right pane of the Registry Editor locate and make double click on the following registry subkey named DEVMGR_SHOW_NONPRESENT_DEVICES

If not, make it. In this case, in the right pane of the Registry Editor, right click in the white space and choose NEW > String Value to create a new subkey.
Name it DEVMGR_SHOW_NONPRESENT_DEVICES
Now, make double click on it.

A new window will be appeared.
Modify the value in the field named Value data.
Set the value for this subkey to:
1 (read ONE) = Show Devices
0 (read ZERO) = Hide Devices

Then click on Ok button.

Exit the Registry Editor.

Restart the computer.