My bufflo external HDD is not run.

[WLMoe08]

My bufflo external HDD is connected to laptop,but cannot run.

 

[dodger46]

Can you see the drive in Computer? If so, Right click on it and choose 'Properties' On the 'tools' tab under Error Checking choose 'Check now' and tick the box 'Automatically fix' etc. If it can't check the drive as it's in use allow a dismount or check when you restart Windows.
If that fails
Winkey + X, Choose Disk Management
Expand to full screen
Look for your Ext drive in the right pane.
If shown, right-click in the area showing that drive.
Click "make drive active" if you have the option.
Click Ok