:
If using Windows 7, In the start search box, enter 'devmgmt.msc' and check if it opens since you are unable to open via control panel.
Have a look and see if you have this file :
C:\WINDOWS\system32\devmgmt.msc
1. Click start
2. In the search box, type 'run'
3. enter 'C:\WINDOWS\system32\devmgmt.msc' and check if the file is present.
The file could be corrupt, I would recommend doing an system file check to attempt to repair this file. Here are instructions on how to do this:
Post back with the status
refrence:
کد:
http://answers.microsoft.com/en-us/windows/forum/windows_7-performance/unable-to-open-device-manager/789dbb1b-241f-4360-832e-0631eae3de60
see this for more info
and this