External USB Hard Drive do not show up in Win 7 64bit

External USB Hard Drive do not show up in Win 7 64bit

Click on Start --> In search box, type cmd and press Enter. 

"Command Prompt" will be opened. 

Now enter the below commands 

set devmgr_show_nonpresent_devices=1 --> Press Enter 

cd\ ---> Press Enter 

cd windows\system32 --> Press Enter 

start devmgmt.msc --> Press Enter 

"Device Manager" window will be opened. 

Now in the device manager, click on "View" --> Select "Show hidden devices" 

Now expand all the nodes by clicking on "+" symbol. If you find any greyed 

entries --> Right click on it --> Select "Uninstall". 

Restart your PC --> Now try connecting your external drive.